Seems to me a lot of your costs are over and above the actual mining hardware.  Even if you return the mining hardware you'll be out a bunch.

Me, I've shut down my miners.  Yeah, I'm small scale -- 561 Mhash/sec, cost me $209.  Not mining at this difficulty until I know if BTC will be > $4 or under .01 once the smoke from the MtGox fireball settles.  =)