Also they have the S3 Plus to get a little more hash then first batches. It is hard to beat the price on them if you already have PSU's. If not make sure to add price of PSU in roi math.
I just got a S3+ off eBay for £200. It's basically unused. I'm running it to replace a clutter of older Avalon-based ASIC boards that drank 1kW for about 180GH.
The S3+ is doing a shade under 500GH with 360W at the wall. I'm very happy to let the S3+ sit and churn away until it pops, especially when difficulty is sitting still. I'm in Bitcoin for the long game - I like many have wasted hundreds of BTC buying pointless ASICs, and the only ones that turned a high profit were the Mk1 ASICMiner Blades. Now I'm just happy to sit and churn away and hope BTC is worth a lot more in 5-10 years time.