I am doing the same kind of work for windows mobile 5, 6 and CE. we have done lot of other work with PDA and handhelds including the GIS, RFID applications.
recently we developed one application for security company which was using GIS, RFID's within the PDA application.
anyways, I can do this job for you with iphone but the budget you have suggested is of my concern. I can pick this job in $1000. I am keeping things open, so if you get someone to do this for you at lesser cost, you can go with him easily BUT if that doesnt work then you can contact me later also at anuj at itglobalconsulting dot com
Cheers