Tulips sprang to mind when I read this thread title. People went crazy for them!
Are you sure it was 1984? We got our first VCR in 1984 - big clunky silver thing, must’ve weighed about 300 pounds - it had a wireless remote with every button except eject. We had it up until the early/mid-'90s. I seriously doubt my parents had $400 at the time or would’ve spent it on a VCR if they did.
My parents taped all the movies we had off of tv because, like someone else said, to actually buy one in the store was absurdly expensive.
The Washington Monument is topped in aluminum… to show the world how rich and powerful America was. Look! We have aluminum. 
I’ve bought full scientific (non-graphing) calculators at the 99 cent store. They were very flimsy and broke easily, but I was impressed they were sold there at all.
Supposed to be topped with Aluminum? It was!
http://www.tms.org/pubs/journals/JOM/9511/Binczewski-9511.html
Yup - I corrected my post - for some reason I thought it was replaced at some point later on. Obviously not. I guess it is too late to replace it with gold.
Interesting about the aluminum cap on the monumemnt – despite all I’ve heard about it being chosen as an expensive itemn, this doesn’t seem to be the case at all. By the time the capstone was cast, aluminum was relatively inexpensive, in fact:
http://www.tms.org/pubs/journals/JOM/9511/Binczewski-9511.html
From precolonial times to the beginning of the 20th Century–Pineapples!
From tropical islands far away the few pineapples that could get to mainland on the old slow ships without rotting were coveted.
*Thus, into the 1600s, the pineapple remained so uncommon and coveted a commodity that King Charles II of England posed for an official portrait in an act then symbolic of royal privilege – receiving a pineapple as a gift. *
When we opened our new office, we ordered 250 calculators with our name and new address on them as giveaways. They were fifty cents apiece.
My understanding is that folks ion 19th century New England grew their own in greenhouses, right here in the northeast. Pineapples became a symbol of hospitality, and you can still see them carved into antiques and into old architectural elements.
They were undoubtedly still expensive (how many pineapples can you grow in a greenhouse?), but not as expensive as they’d be if you had to rely on a precious few to not spoil on the long trip back from the tropics.
Ball point pens. They cost $20 when they first came out. That would be somewhere over $100 today.
A laser beam. They were truly exotic and unobtainable. Now you can get a laser pointer for a couple of dollars and all kinds of cheap electronic goods have lasers in them.
Restaurant food. Sister Carrie made $7.50 a week and a restaurant meal was about $1.50.
Now people who bring home $500 a week can get a meal for $5.00.
Since someone mentioned eyeglasses, weren’t contacts once expensive? I don’t have glasses or contacts but I seem to recall my sister getting a pair of contacts for around $200 about 20 years ago. My last girlfriend got a whole case of them for about $100 recently.
Remember when you had a manually-tuned FM radio that drifted? The first PLL radios cost a bundle-more if they had a digital frequecy disply-now even cheap radios have this stuff.
What amazes me-they still make oodles of cheap AM-onlr radios-yet I NEVER see people using them-where do they all go to?
And she still is! (Or were you talking about the stone?)
So, was placing Opal third in your list by brilliant intent, or a wonderful coincidence?
During WWII the urine of patients given Penicillin was saved so that traces of the drug could be extracted and reused.
Until about 40 years ago many schools, YMCAs, and Boys’ Clubs required men & boys to swim in the nude. One (of several) reasons for the practice was so that boys who couldn’t afford swimsuits wouldn’t be singled out. These weren’t coed either.
Modern clocks.
I recall listening to an podcast of the Thomas Jefferson Hour where an in-character Jefferson was discussing that Lewis and Clark carried the finest Swiss chronograph possible, which back then cost a tidy $250 (which back then cost damn near a fortune) and drifted with accuracy on the order of a minute or so, plus or minus (IIRC).
Nowadays, you can get a digital wristwatch for $10, which keeps the time orders of magnitude better’n the old mechanical clocks.
Tripler
Hell, you can get a calculator on 'em too!
Along with radios as someone previously mentioned I would also add stereos. You can get a nice little system these days with great sound, multiple options like CD, MP3 and even turntables, and they can fit on a bookshelf.
Would Costco work for you?