i know a few people who have this problem--a couple to an extreme amount. i have certainly dealt with it too, though not as much. usually, if i find something i think i'll be interested in, i try to find a way to just try it out since i don't really know if i'm going to stick with it. the internet really comes in handy here; it provides the opportunity to learn about a subject without pouring a whole lot of money into it. it took some practice and discipline, but i've gotten really good at finding an interest, learning about it, and waiting at least a week or two before i spend anything on it. it doesn't really do a whole lot for spontaneity, but it helps. i could easily pick up a new hobby every week--which i don't necessarily consider a bad thing--and this helps keep things in check a bit.