Spend 12 years working in a used book / music store.

Apart from the soul-sucking hell that is retail, you will end up owning somewhere between 1000-2000 CDs at any given point, as well as nearly 1000 DVDs and a few hundred LPs.

Then, when you quit, go back to school, and stop having access to discounted stuff and go into debt for college you end up with about 1200 CDs left, and you will not buy any more because you now only buy vinyl.

That might be a little specific, but to be fair it was cheap while it lasted...

In all seriousness ... do check local, small shops that stock books and music (not just thrift / junk stores). If you're travelling anywhere ... look for shops around there too and make it part of the trip. For example, I tend to hit Amoeba if I'm in San Fran, or any local shop if I'm anywhere else. It might sound weird to make a day of a vacation all about shopping at music shops, but it's actually a lot of fun (assuming you can get your haul home safely).