Solo Mining Cost: 1 week to find a block of 40 at 100 watts/hr at 0.10 per KWH => $1.60
Solo Mining Revenue: 0.004 BTC * 40 * $300 => $48
Profit: $46.40 per machine!
Difficulty will adjust in 12 hours or so... changing the equation slightly:
Solo Mining Cost: 1 week to find a block of 40 at 400 watts/hr at 0.10 per KWH => $6.40
Solo Mining Revenue: 0.004 BTC * 38 * $300 => $45
Profit: $39.40 per machine!
At these prices people will be throwing everything they can get at mining this thing and that means increasing the hash power by 28x assuming the price remains constant...
Yikes!