I'm in the UK.
OS: Ubuntu 13 - free
Mobo: Asrock 970 Extreme4 - £30
GPU: 3x Asus DirectCU II 7850 - £150
RAM: 4gb - £20
PSU: 850w Corsair TX850M - £50
CPU: AMD Sempron 145 - £20
SSD: 32 gb - £30
total: £300. In my book, that's about $500. If you want to remove your head from the clouds / put down the crack pipe, I'll offer you $500 including delivery as your original price is just crazy talk.
They go used on ebay for like £75-90 each. Where are you getting £150 for 3 from? Also that motherboard is going for £50 used and £80 new. The psu is also worth like £90 so probably £65-70 used. I might be able to get those parts that cheap if I start following some of the trucks near my town.
Because they have been hammered as a scrypt miner, there is probably no warranty left, no mention of h/w errors, no mention of what temp they have been ran at, so they'll need to be dismantled and new TIM applied.
$10 a day. Unless your electrickery is free, there needs to be movement on the price.
I visit PC markets, fairs and buy at the right prices, buy items in sales/offers/topcashback/quidco/credit card cashback/etc etc. There's more to buying than waltzing into a shop and handing over your hard earned.
All the used mining kit for sale on here will have been taken close to it's design limits. So, my prices aren't perhaps generous but would you rather spend £30 more and get a brand new mobo with warranty etc or save yourself £30 and risk it breaking down with no recourse?