They sure were great miners. Probably the best I've ever owned.
I had luck selling mine locally on Craigslist. I tried selling it online but nobody wanted to pay $20-30 to get it shipped.
But good luck with sale.
Yeah, i bought mine for 20CAD few months back and it was part of a bigger deal and was done locally. If i had spare power, i would jump on buying old hardware on freeish electricity.
I managed to make my S5's quieter than a stock S3, but i still prefer the S3 because you can make it completely silent with 20dB fans.