I bought one locally for $100 with the PSU included.
My price is crazy? No, the price you paid was CRAZY low. Good catch I have to say!
Going by what I see them advertised for and then selling on Craigslist and on Ebay, at an ASKING price of $200 an S2, I'm right in the average price range. But ALSO, my price is an ASKING price.... a purchaser can negotiate.
However, I'm not so certain that I want to sell them or recycle them though. I had a mad scientist moment last night and farted around with some clockrates, voltages, components and whatnot... at one point I had an S2 running at roughly 0.6W / GHs for an hour, stable. Obviously the hashrate was lower than 1TH but it was more efficient than in the factory configuration and using the coinwarz calculator, if I had a power supply that could handle continuous use (I have a lab supply that I adjusted lower than 12vdc), I would be able to pull a profit again with these using my home electricity. I had to abruptly stop the testing because I was starting to smell my power supply cooking.
Now, if you rent an office or storage unit for $100 - $200 that has electricity included in the rent, ( That what I was doing with these S2's, they just came home after my lease expired ), you automatically pull a profit. At my asking price, with no modifications, stock 200Mhz config, running 4 of the S2's, ROI for the purchaser is less than 6 months. Try to lock in a 1yr or 2r lease and there you go...
That is probably what these S2's are good for now ... find the free energy and you have your beer money for the month.
BUT, if I can get consistent better efficiency with the changes that I'm making, I think I'll keep them and make a "How to" article .... How to say The S2 .... IT'S ALIVE!
Maybe that was the case one month ago, but now for 200$ you can almost start picking up S5's so it doesn't really matter what kind of scenario you play out and tell others they can ROI in 6 months.
You can buy S3's and ROI them in 3 months and they will last longer since they have better efficiency.
To top it off, your S2's does not even come with a PSU.