I have a small network set up using a modified version of app_rpt. I use my own registration server so there's no dependency on the AllStar network, and no way to accidentally connect to a Ham repeater. By keeping them separate, we're in compliance with the FCC regulations for GMRS in that we're preventing unauthorized access. You just need a PC you can wipe clean and put Linux on (or even a Raspberry Pi), and a piece of hardware to interface with the repeater. We've used the URIx board from DMK Engineering (about $70), and the RTCM board (no PC needed, but more expensive at about $270). The RTCM is tricky to set up but the big draw is that there's no need to alter the firewall settings at the repeater site (some people have no way to forward ports). If that's something you're interested in, let me know and I can PM you with more details.