It looks like they are $2.10/hr and you get two teslas at 90Mh/s each, plus some number of 'cpu compute units' say another 10Mh/sec, bringing you up to 190Mh/sec total. The average time to generate a block at 190000 Khps, given current difficulty of 16307.48285682 , is 4 days, 6 hours, 23 minutes, and 52 seconds. So at $2.10/hr thats that means $201.6 for four days of work to get 1 block. A block nets you about $20usd at the current exchange rate... so not very worth it.

At today's difficulty of 55590, the average time to generate a block at 190000 Khps is 2 weeks, 0 days, 13 hours. Assuming the same rate of $2.10/hour that's about $730 to generate 1 block.

The difficulty is expected to change in about 1 day and 8 hours from now, and it's estimated that the new difficulty may be over 77700. The average amount of time to generate a block at 190000 Khps would then be 2 weeks, 6 days, 8 hours, which would bring the average block generate cost to $1025 per block.

At the current market price, 50 BTC trades at about $45.