mine with it for 60 days then sell it.
why is it 60 days ?
60 days will probably net you about .75btc from mining . eBay you will probably net $600 after shipping and fees
So the miner costs you $550 in btc you make $50 profit there and you still have .75 btc =$400
$450 profit ROUGHLY without breaking out a calculator.
Phil is better with the actual numbers then I am.
After 60 days it will not go for $600 though you might get $450. Then take $50 in ebay fees.
You still you could make $250. But I doubt you will make $450.