Haha, I am 31- I also noticed everyone who responded is in the same 'generation,' my theory being we were all exposed to the best vgm during our peak gaming years: 10-14. From SNES to Playstation is when soundtracks were like a slap in the face compared to what we started out on for the NES. Just a possible interpretation anyway.
My first soundtrack purchase was also from the back of a Gamefan magazine, and it was Seiken Densetsu 3. I remember being wowed by Secret of Mana, so I thought the next iteration would logically be better, but I think 2 is probably the superior soundtrack, though 3 has lots of shining moments.
I have been collecting for only 2 years though. Apart from that early purchase, I never had the income to really pursue my interest. I would periodically look on ebay at things like Super Mario World soundtrack or Super Mario Land soundtrack (I love world 1 bgm), but it was strictly window shopping until only recently I was able to take the plunge. I have a lot of catching up to do, but I already snagged a bunch of cool stuff, and being late to the game I also get to take advantage of cool resources like VGMDb, SEMO, OSV, amazon.jp, yahoo auctions, middle-man services and you nice folks here Only downside is now Super Mario RPG and Yoshi's Island are pretty much off-limits.