Without power costs, they make $111/year at current diff, block reward and btc price.
I strongly believe that the diff will rise, i'm not sure if the price will rise to tough...
http://www.coinwarz.com/calculators/bitcoin-mining-calculator/?h=450.00&p=366.00&pc=0&pf=0.50&d=521974519553.62800000&r=12.50000000&er=1408.60000000&hc=0.00If we factor in a small power price of 5 cents/kwu, it'll cost a miner about $160/year to run these machines while only make $111/year in btc (and dropping).
http://www.coinwarz.com/calculators/bitcoin-mining-calculator/?h=450.00&p=366.00&pc=0.05&pf=0.50&d=521974519553.62800000&r=12.50000000&er=1408.60000000&hc=0.00The current break even power price seems to be 3 cents/kwu or less... It'll even drop further in the future as the diff goes up. If you pay more than 3 cents/kwu, you'll lose money while mining, if you pay 3 cents you'll make $14/year profit at current network conditions and price...
http://www.coinwarz.com/calculators/bitcoin-mining-calculator/?h=450.00&p=366.00&pc=0.03&pf=0.50&d=521974519553.62800000&r=12.50000000&er=1408.60000000&hc=0.00Long story short, i (and maybe other people) would be willing to buy these S3's (if they are in good condition) either as a toy to tinker with, an educational tool, a conversation starter, part of a collection, or as a loud space heater... Either way, i wouldn't give more than $10-$15 for one piece, escrow and shipping included. If i'd buy 4 or 5, i'd even expect a discount.