Ha, @Si_Amigo said “I’d have more to worry about from the hookers due to no penicillin being available”. So when I said “bring some with you”. I should have specified I meant penicillin, not hookers. And when I said for personal use only, don’t introduce penicillin to the public before WW II. It might seem like a kindness, but who knows how it will mess up the timeline, dagnabbit.
I knew what you meant. I just liked playing with the options your ambiguity afforded. 
And no, if I’m bringing my own hookers back they’re personal use only. I’m not sharing them with the locals; who knows what those folks are carrying?! :eek:
Which raises an interesting digression:
When traveling geographically, we say have “visitors” and “locals”. When traveling in time, we have “visitors” and “_______”? Hmm. Gotta think about that one a bit.
“There’s a sucker born every minute.” – P. T. Barnum (d. 1891)
It worked for him.
You think there would be a market for pornography in the old west? Photos existed but we super expensive to acquire, how much money could I make selling my Inherited collection of Playboys and selling each nude page separately?
Unless you are unlucky , the older and younger banknotes won’t come together while they can be traced to you.
If you print them yourself, they will lack watermarks.
Could I buy watermarked paper and print my own counterfeits? It’s not as if I’m counterfeiting any modern money.
I saw a documentary about Lincoln. From Wikipedia:
With a reported one third of the currency in circulation being counterfeit at the time,[13] Abraham Lincoln established a commission to make recommendations to remedy the problem. On April 14, 1865, the day he was assassinated, Lincoln signed legislation that created the Secret Service. The Secret Service was later established on July 5, 1865 in Washington, D.C., to suppress counterfeit currency.
So the possibility of counterfeiting was well-known to yokels and slickers alike.
In fact IIRC it was a group of counterfeiters wanted to get one of their gang out of prison. Their plan was to steal Lincoln’s body on election night and ransom it, hoping to spring their guy. But one of those inside the plan betrayed them.
I probably missed it upthread but in one of the Back to the Future, Biff had a book of sports almanac. Any time he needed money he could bet on a winner. Taking back something like that, or knowledge of stock market outcomes, would be easiest. Bet on a few losers so you don’t look too good…
No. Why do you think there were the first diamond rushes in the first place?
De Beers inflated the value later, after larger deposits like the Namibian were found and also the relationship with kimberlite pipes became better known, greatly improving prospecting and availability of industrial-grade diamonds. But in the late 1800s, diamonds were plenty valuable. Not to mention the other, currently dirt-cheap, gemstones Darren_Garrison mentioned, like sapphire and ruby.
Here’s more than anyone wants to know about historical gem prices, but TL;DR version : if you want to do OK for yourself, take back a few handfuls of >4 carat synthetic rubies. Like, laser rods or somesuch. Just be circumspect in how you sell them, and probably aim to be in Amsterdam or New York or some other city with a good gem district.
@lobotomyboy63, interesting info about counterfeiting and the Secret Service. I still think that creating counterfeit notes would be doable. The anti-counterfeiting methods that the late 1800s Secret Service employed were probably relatively primitive compared to what we can do today. Maybe treat the counterfeit bills with a chemical that causes them to slowly degrade over time so they don’t survive too long after spending, just to make sure they don’t mess with the timeline.
@MrDibble, great info about gemstones. This also sounds like it would work. The only problem might be when someone tries to sell or appraise their synthetic gemstone in the modern day.
“This gemstone belonged to my great grandfather. It’s been in the family for 140 years!”
Jeweler: “sorry, this is a modern synthetic stone. Can’t be that old.”
“Whaaa…?”
How about lab-grown diamonds? My understanding is that they’re indistinguishable from the mined kind, except for the laser etching to mark them as lab-grown, and they’re considerably cheaper. Would they seem anachronistic if they were examined 140 years later?
Or I’m trying to imagine something valuable but perishable that one could bring back, that would be sure to decay before it became obvious that it’s not from the right time frame. Some sort of fresh food, perhaps.
That’s going to be a problem for a lot of these…
“These stocks are printed on an inkjet, what are you trying to pull…”
Many medications fit that profile.
NSAIDS
Worm meds
Antibiotics
Viagra
Modern antacids
Lidocaine (and similar) ointments
Anti fungal ointments
All have relatively obvious results and I’d think you could get a pretty penny for them.
One thing to be careful of is the packaging. You’d want to avoid bringing them back in modern plastic pill bottles.
Sure, but how much Viagra could you realistically sell as a traveling salesman, and would that be enough for whatever level of luxury you want?
I think the real money would be in doing things like selling Viagra as a patent medicine, and using the proceeds to buy into whatever company Patillo Higgins had at Spindletop. Or maybe just buying mineral rights to various future oil fields of the late 19th/early 20th century and collecting royalties on the oil extracted from them.
Contemporaries?
I like that this is a consumable and thus wouldn’t stick around to the present day, like a synthetic gemstone might (hey, check it out in the loupe- this ruby my great granddad claimed he brought back from a trip to The Orient in 1880 has a little serial number laser-etched onto it. Weird…).
But it doesn’t quite fit my two conditions- not mess with history too much, and be something that could be spent, sold or traded from day one of the time jump.
I mean, you’d have to buy or steal a wagon, paint “Dr. Smith’s Miracle Cures” on the side, hire a shill to hang out in the audience as a volunteer or a testament that it worked miracles for them (even though it actually does work, you need to initially convince a crowd that probably got burned with snake oil in the past). Then spend a lot of time traveling from town to town selling your wares.
Also, with all that viagra getting distributed there will probably be a number of unintended pregnancies that wouldn’t have happened, and who knows how much that will affect the timeline.
Chronisms.
This is what’s been bothering me. Selling anything that’s easily portable and high value means finding the right buyer or the right marketing to create buyers. That is hard to do without violating the Temporal Prime Directive.
So we want to find something that has a large market (so no long searches to find buyers and the best prices) and is a consumable commodity (not easily traceable into the future), but portable and lower relative cost in modern times vs the past.
Maybe high quality liquor? There’s a market for that everywhere, but we need to find something cheaper to make now than in the past.
Hmmmm. I think I’d take pockets full of Penicillin and Viagra along with my knowledge of the fairer sex and work part time as a gigolo, serving the wealthy women of the day. 
If you want something that would at least break even with your inflation calculator, be untraceable, and be unlikely to effect the timeline (or get you caught for counterfeiting) may I suggest (as long as it’s prior to 1893) silver?
Before gold became hyper-dominant, silver was also a prominent metal based currency and valuable, which being less conspicuous than gold. And until 1893 when it was repealed, there was a purchase requirement that helped keep the prices high ($.83 per ounce which could be purchased today at @ $27).
This isn’t going to ‘make it rain’ but would be less likely to be of note. If we’re restricting it to what you have ‘on person’ it’ll be enough to get you a solid, immediately spendable stake to invest or otherwise exploit knowledge.
For that matter, just knowing that silver is going to go from $.83 before the repeal to $.63 after, you could arrange to purchase silver after the crash (using whatever investment scheme you had used) and become a quiet partner in various mines that had lost a quarter of their value overnight, and have a steady and explicable source of income after.
Sorry for the focus on silver, I spent quite a bit of time in one of the Colorado boomtowns and it’s kinda pounded into you.