I thought there was a post titled geartrade.com but I didn't see anything written ... that's my top suggestion.
There might be a caveat on geartrade, but you can usually find high quality gear for really cheap, and you don't have to wait like you do on eBay, BPL, etc because so many retailers use it to sell returned items. The gear is usually lightly used or open-box. I just got a North Face 800-fill, 10 oz down jacket for $63 (msrp $229), it will need a little bit of stitching, though.... But I don't think I could even purchase a jacket's amount of Pertex for that price.