Coolant Heater Storage Tank

I just drove my 2006 Prius from Dallas to San Diego. Unfortunately, as I was pulling into a hotel parking lot in Arizona at night I didn't see a drainage ditch right to the side of the driveway and ended up going down and against the concrete drain wall. The bumper is being replaced and they told me a the coolant heat storage reservoir tank most likely needs to be replaced (has a dent in it). They are quoting $1,000 for the part. Is this a fair price? Can anyone recommend a mechanic in San Diego that works on Prius' or should I stick with the dealer?