S3 is already up for sale, at about $1/gh and 0.77w/gh.

2TH from the Antminer S3 (4 units, being BTC0.75 each) would only pull about 1560w, and cost $1935 (as of BTC price being $645 when writing) without the PSU's, so you must add in the cost of PSU, which maybe about another $200... so total costing about $2135 for (what seems to be) much better build quality, and most likely much better functioning product.