This one might be a deal if you need short-depth chassis, as that market is fairly small. I don't know how low you'll be able to negotiate for a single unit, but I've been able to get $150/ea for an order of two and $125/ea for four. Although this is still a fairly large price (a new SC523L-505B) is $250, I'm assuming that I'll be able to sell of the motherboard, cpus, quad port network card, ram, etc. for a reasonable price and obtain a PWS-351-1H (~$25) or PWS-441P-1h (currently ~$70) power supply for cheap to replace the existing PWS-521-1H (which is fairly loud). No HDD caddies are included, but you could either use velcro or order the MCP-220-00020-00. Please note that despite the MCP-220-00044-0N being listed as an optional item for dual 2.5" drives, it is too tall to allow the chassis lid to be closed.
SuperMicro SC523L-520B 2x Intel Xeon E5620 12GB RAM NO HDD G200eW WPCM450 | eBay
SuperMicro SC523L-520B 2x Intel Xeon E5620 12GB RAM NO HDD G200eW WPCM450 | eBay