Yeah you kinda missed the boat I sold all my 1st generation crap on eBay about a month ago and actually did vary good made 3,000 dollars back !!! If you mine bitcoin you have to keep a close eye on eBay auctions prices !! Thats the only way You can make ROI and be able to stay in the game and buy more hardware...
I've started on eBay to get my mining hardware so that is sooooo true!!
Recently AntMiners are going for less than 80 USD a pop and dropping ( U1 not modded ) and with my current set up i'm under 6GHash/sec Sha mining and it's either dump more USBs at it to try and get 10X mining speed to keep it viable for another year or sell it while the erupters/Ants are still worth close to what I paid for them ( or wait until they are useless and sell them for what I paid like some Icarus boards seem to be selling for on eBay ).
To conclude, it all depends on 3 factors per individual, BTC income VS power cost VS hash rate.
If the hash rate is too low, check to see how much of the new tech you can buy with selling off the old ( and potential power savings and increase of hash/same hash ). I still have 2 old Nvidia cards I won't let go of that can mine but only since they can be ' backup ' video cards for my systems ( 8600GT and a 8400GT PCIe x 16 ' compatable ' ). Not every miner out there can say they bypassed the power costs by going green tech ( solar/wind/battery + inverter ) to have the ' actual power ' cost the cable modem.
Every miner out there will have to ask themselves " is it worth this power cost to get this much coin per month in this much space " at some point.