Whittling.
Say, for what it’s worth, a friend of mine is an amateur auto racer. He tells me that all you need to create a small fortune through racing is a large fortune.
You see, only an intellectual will point that one out. 
Ahem, it’s $15 a year. So it’s CHEAP. Less than a nickle a day.
I forgot I even paid to sign up. :smack:
aw too bad. I really wasn’t meaning to be nitpicky, just momentarily confused and cautiously hopeful. Thanks for answering.
Oh well. See y’all again in more prosperous times.
Gold panning. I like being outside, but I’m not big into hiking. I don’t eat fish, nor hunt.
Sitting by a stream looking for those shiny speaks intrigues me.
Surrenderdorothy, last time I heard, the SDMB became free. If you have a free membership, you have to put up with ads.
Or was that still going to happen? I lost track a bit.
No, don’t go! It is free to post if you don’t mind seeing ads.
Computer programming doesn’t have to cost you anything provided you’ve already got a computer and an internet connection.
The MMORPG City of Heroes (http://www.cityofheroes.com/) provides unlimited hours of entertainment for only $15 per month (in addition to the cost of the game, which runs about $20 for both City of Heroes and its companion City of Villains).
My partner plays World of Warcraft, which I believe has a similar monthly fee.
No! It’s free now! You just pay if you don’t want to see ads! Don’t scare them off!
But in the spirit of Halloween time, I had to try…
Thanks for letting me know this. I was completely unaware. Either way I’d probably still have made the donation.
The Kingdom of Loathing is a fiendishly silly and addictive online role playing type game and it costs nary a farthing!
Hiking and biking are about as cheap as it gets.
Gardening can be expensive but it doesn’t have to be. Seeds are very cheap and manure can be found anywhere–plus, composting is good for the environment and you can start a worm farm for pretty much nothing, then sell the worms back to a bait shop! Win! Not to mention all the free food, and if you go organic it’s fun to find a farmer’s market to sell your extra veggies, again win!
Blogging–sometimes, if you get good at it, people even pay you to annoy others with your opinions. Can it get any better?
Digital photography–cheap 8 megapixel digicam and Gimp, and the world is your oyster.
-Always considered blogging since I am always on a computer. Just didn’t know how to approach it.
–Is Gimp and better than Photoshop or about equivalent? I’m pretty decent with Photoshop. Flash is fun to mess with too.
How can gardening get expensive? I can get a plot for $10 per year, and seeds/plants for about another $15, and then maybe $20 up front for a spade, hoe, and hose that last for many seasons. That hardly even adds up to the amount you’d pay for fresh vegetables from the store, and the ones you grow yourself are generally going to be much better than the store-bought ones.
Personally, $15 per month is out of the range I would consider “very cheap”. Other computer games can be quite economical, though, if you have the computer anyway and don’t mind re-playing them. I still play Starcraft and Diablo II after a decade or more, and they only cost about $30 each.
A good note, if you ever give up on your hobby you could be quite usefull if a room you are in ever suddenly fills with smoke… as you’d be an ex-tractor fan.
I play RPG’s and board games. Most expensive parts are the snacks.
cough library card cough
I’m pretty sure bait worms and earthworms are two different kinds of worms.
Reading. The public library keeps it free, but honestly I probably have a lifetime supply of books in my house already.
Cooking can be a cheap hobby. You have to eat anyway, and you can definitely cook something good for the cost of fast food or processed mixes. As a hobby cooking can turn expensive on you, though.
Volunteer work. Transportation costs are usually made up for by the occasional free meal and t-shirt.
Whittling. Sticks are free, and I just pick a pocket knife of the many I’ve got.
I’m a railway enthusiast. This can vary from being a hugely expensive hobby involving world travel, organised steam excursions, regular recreational long distance rail journeys, high tech camera gear, multiple magazine subscriptions, vast libraries of books, or expensive model railways (if you’re into that). Or it can be just a love of rail.
For mine, I just enjoy rail travel when I’ve had to do it anyway in order to get someplace, and most of the social aspect of it in the enthusiast community I do online and for free. I’m not a photographer or trainspotter, but I do spend a lot of time devoted to rail in various ways. I’d have to say I’ve probably spent under $500 in the last ten years on it, for thousands of hours of enjoyment.
I follow Long Distance Sled dog racing…short of moving to Alaska the internet is the ONLY way to do it. I help moderate a board and participate on several others.
It IS gonna get expensive though as i plan to attend the 2010 Iditarod as a 50th birthday present to myself. 
Another “hobby” I have is I like to “post watch” here…I like deciding who I would want to meet and who I think is a total dill hole…costs me nothing but and internet connection which I already have for the sled dogging thing. 
ThisSpaceForRent
http://mushing.bssd.org/forum/