well you could get a replacement Radiator from
www.thepartsbin.com for around $125. Thermostat can be found really cheap too, and can easily be changed by yourself in your driveway in under 15 minutes.
I personally would do the radiator swap myself, but if you don't feel up to it, I'd at least search around for a cheaper mechanic. Dealerships and Honda certified mechanics will charge $70 an hour for labor. If you find a decent private mechanic, labor charges will be alot less. Call around in your area, and try and get a few different estimates.