Wireless DC voltmeter

I'm looking for a DC voltmeter I can connect to the + and - terminals of my deep cycle battery located outside my house and send the data to either a device with an LCD output or computer via any kind of wireless transmission. Does such a thing exist at a cheap price? ( 50$ or less ) or would it be hard to build one? Let me know either way, thanks.

PIC's and licence free radio modules, fairly straight forward to do, and all the parts are covered in my tutorials.

While doing something like this you may as well send more data, such as battery temperature, ambient temperature, current drain/charge etc.

Can you point me to something easier to understand? Or something I can buy? My knowledge of electronics is limited. I just need to know the voltage of my battery from a remote location (less than 50 feet). I allready bought a temperature wireless transmitter from circuit city so I just need the voltage now.

thanks