free power = faster return on investment.

An s-3 doing 480 gh at free power earns close to 30 usd a month.

So if you buy 2 you earn close to 60 usd a month.  coins are up so they cost more then last month

the cheapest I see on on ebay is 110 with shipping

so 2 plus a power supply = about 300

and you would have your money back in 5 months.