The spot prices for GPU instances are very good. I think that a improvement in the tsiv miner for the grid card could make it profitable using GPU + CPU.
@tsiv, if you would like to test in a EC2 instance I can setup one instance and give the credentials so you can log in and run the tests you need.
Just let me know if you want to run some tests.
If anyone need a guidance on how to get tsiv miner running on EC2 instance I can help.
if you could put a tutorial somewhere, I'd be interested in trying (but not right now...)