That looks like a fair price. I'd ask to see a few other homes with g! installations by that company, and would try to speak privately with the homeowners. If the installer is relatively new to the system, I don't think it's too much to ask for a couple of visits in the first 6 months to tidy up loose ends AT NO ADDITIONAL CHARGE. With this in the contract, they will be more likely to do everything right the first time around, and won't get charged later for things that should have been done correctly and confirmed the first time around.
I'm overall very happy with my g! setup, but there are still a few kinks being worked out 8 months later, mostly because the installer and electrician did not communicate well on site during construction. In retrospect, I wish we could have had the electrician who works regularly with our AV installer do our whole house. On the plus side, our installer gave invaluable advice on modifications to the lighting layout in our home. Put in more recessed lighting than you think you'll ever need, then just dim it with your Ra2 to taste.