Don't forget that there are EBay fees, Paypal fees, shipping costs, fees to turn that fiat back into BTC. I've had zero feedback bidders not pay, resulting in more listings, and the fees just keep starting over. Overall it's a really inefficient way to move these units.
Granted there are Ebay and Paypal fees, but shipping costs should be paid for buy the buyer, and the BTC buying fee should be pretty minimal if you use the right source. Also, a non-paying bidder just means a waste of time, as there would be no fees involved when ebay refunds the final value.
Overall though you will only see any profit in these units if you buy them in one of the group buys and sell them on ebay in the next few weeks. Let's do the math. Using
https://bitclockers.com/calc, at current difficulty, 1200 Mh/s will return .0539 BTC per day. 1 unit can do 300 Mh/s, which would equate to 0.013475 BTC/day from a single miner. The group buys are going for about 2.15BTC.
The breakeven point, assuming no difficulty change and no electricity cost is 159.5 days
Factor in difficulty increases and forget it. In 3 months the difficulty will be so high these will be generating next to nothing.