ohh boy. Stopforme, you are going to have a blast with this post. although I too agree some of these are a big waste of time/money.
I've had so many hobbies that actually finding a hobby is often a hobby of mine.
At one time I was a "magician" I had doves, fire boxes, rings, swords, the whole nine yards. This crap was way too expensive, although, at the time it was very fun and some of the stuff was/is still super cool.
I grew bonsai trees for a few years... not very expensive, but it was a slow process and all my trees died when a "housekeeper forgot to water them.
pogs-well wasn't everyone into these at one point and time?
I've always collected stuff- comic books, star wars (mainly darth vader) stuff, -now titans memorabilia
Remote controlled planes- very fun and very hard-also very expensive (especially if you suck at it-there IS a reason i'm scared of flying on planes)
Lately i've been working on my car's sound system, and other car-related mods. Of course there's the Titans games/tailgate parties. Burning a ton of mix CDs. Making Features ringtones

and it seems calling sprint with problems is quickly becoming a hobby of mine.