I'll try and help you out here. Do you know how trying to build a complicated, secure, money making site for $700 (at a time) is going to end up costing you a lot of money?
You are going to pay these offshore guys in India $700 for a piece of crap that doesn't work (but is probably built to your precise specifications, you just don't realize how your precise specifications will need to be modified) that won't be usable. So then you'll start over, with somebody else, probably for another $1000 (because you realized that $700 was not enough) and the same thing is going to happen (because $1000 is still not enough, you are just trying to do it on the cheap). By this time, you might have learned your lesson and go with an agency that, while probably not as cheap, will assure their work and end up paying them $5000 or so.
Total Development cost: $6700
You could just skip right to the end and pay a total of $5000 or so.
You want a money generating adult site built for $700? I want to win the lotto and go live on a boat....oh well.