15 dollars an hour? That is not a fare rate for this type of work at all. I am assuming you are not working thru a consulting company or contract agency because you would be making 30+ an hour at least. The question is not what the app is worth but what is a fair rate for your time and skill set. If you can program in perl and know MySQL you are being way underpaid. It also sounds like a relatively short term gig so that should boost your pay rate even more. A simple search on Monster or Dice will give you a good idea what the rates are.

cheers,

Jeffery