Step up past the loading dock and walk right into the back-alley spot that is Friends of Sound. They've got a massive collection with all of the classics that you know and love (even Liz Phair! Nay, especially Liz Phair. Just admit it.). Plus, they buy and trade records, and they've even earned Power Seller status on eBay, so at least it won't feel like you're making a back-alley deal, even if that is exactly what is happening.