Looking for easy and cheap Mobile Site

Does anyone know of a good place to purchase and use a mobile site?  I want to create one where borrowers can calculate their payments while they are out on the road and even email me their info so I can get them a prequal

Any suggestions or ideas would be great.  Ultimately, I want to have an easy site that people can use when they scan my QR codes!

Thanks for your help.

KW