Thing is, you can order the DEC batch from Bitmain for 0.22 BTC along with it's PSU, i wouldn't pay more than double for a used one, personally.
How about Ebay as well.. ... Listings across the world for units shipping now under 3k and the seller eats ebay and paypal fees (something like 15-18 percent total). Ebay tends to have the highest secondary market prices around, so you would need to be under these if your doing a direct sale and accepting BTC with essentially no fees to make it worthwhile for the buyer. Otherwise, why wouldn't they just go to Ebay.... just my 2 cents and I do feel that everyone has the right to ask for the price they want and negotiate from there
