2004 Honda Odyssey Repair costs

Have been having problems with transmission - jerky motions, esp when putting it in reverse. The dealer is quoting $ 3,000 for rebuilding the transmission and to fix the rear engine mount that has cracked.
Is this a fair estimate?
If not, where else could I take the car for a better price and quality work?
We live in northern orange county, los angeles area.

Thanking you,

Pranav