Setting up a repeater - advice?

There are plenty of Ham repeaters in my area but no GMRS repeaters. I live in a semi-urban but also heavily treed area with decent elevation fluctuation. Does anyone have experience setting a repeater up and have you tried doing it with other people? How would you recommend going about not doing it alone/making it as affordable for everyone as possible and how would you go about finding the right location? I think that once we got a repeater up in the right spot, we would be able to Tx/Rx really effectively and it might take care of my hate for texting! Thanks