Ouch, cloud credits at $180/M. That's 0.18c for 1000, or 100s of compute time. $6.50/hr for computation, and that's buying in bulk, it's almost $11/hr if you buy in blocks of $15.
Cloud credits come with each plan, as well, so you have some leeway for development and testing before you have to buy additional cloud credits at a base price 0.03 cents per credit.
http://www.wolfram.com/cloud-credits/ has more info.