Fitz, you can get decent frs/gmrs radios in hunting supply stores, usually <100 per pair. You want the ones that claim a 35 mile range, they should be adequate for the 1sq mile area.

Keep in mind that those radios are not scambled and anyone can listen in. Those privacy codes are just 'squelch openers', not really any sort of privacy other than you don't have to listen to people that are using a different squelch code.

Generally speaking, you can count on 1 mile per watt with vhf/uhf handheld radios. Alot of those very inexpensive radios only radiate 500mw, or half a watt. Good for kids at the park and things like that.

Here's a fancy chart that explains some differences better than I can