Remember, if you want to be able to talk to people on the GMRS / FRS channels, make sure to get a UHF radio in the 400-470 MHz frequency range. Bear in mind that if you use a 4 or 5 Watt UHF radio on the FRS only channels (Channels 8 - 14) or on the shared GMRS / FRS channels (1 -7) anybody using a cheapo FRS radio will be able to hear you, but if they transmit you may not hear them since they may only have 0.5 Watts of transmitting power.
The GMRS / FRS frequencies are from 462.5625 MHz to 462.7250 MHz range. See the stickied thread
If you don't want to be bothered by anyone on those channels, then punch your own frequency. Just double check that you don't accidentally use a frequency being used by someone else.
Techseller is a good retailer for radios.