Find a used commercial UHF radio that has Part 95 certification.
Back when I was active on GMRS, I used mostly Icom commercial radios.
Most Kenwood mobiles have Part 95, so they are a good option, also.
You'll have to program them yourself, but with Icom and Kenwood, that's pretty inexpensive. You'll need the radio specific software and cables.
If you haven't programmed commercial radios before, it can have a bit of a learning curve, but as radios go, the older Icom and Kenwood's are pretty easy.
For the base, just get a 15 amp 12 volt power supply.
Make sure you consider your antenna system. It'll make the biggest difference in how well your system performs.
I completely concur with Matt. I was a Motorola guy for many years. I am now team Kenwood. They make an excellent, heavy duty, price competitive product. I own both Kenwood mobiles and portables and I will never purchase anything other than Kenwood in the future. They are easy to program and last forever.
You may consider a Kenwood 8160. They cover the GMRS band, have 128 channels, 45 watts. I own one and LOVE it. They sell for around $120-ish on E-Bay.
Where do you live? I have both the software and cable to program it if I can help.