An auto dealer has asked me if I would create an Android app for them. They already have a good website with images, prices, details, etc. I'm not really sure what all they would want, but for now, I'll will mostly deal with letting the users search through the cars and maybe adding a calculator and a couple of other small features.
I have never written anything for anybody before. They are wanting me to give them a flat price, then pay some each month to keep it updated. How much do people usually charge for something like this?