Cost to replace motor and transmission mounts?

Are you sure the vibration is caused by "bad mounts" and not brake rotors that are out of true/warped? Engine mounts are $50 to $60 each and about 2 hours to replace both (in total).

Paynes Automotive can diagnose your problem for $47.50 and give you and estimate of exactly what it will cost to fix your vehicle. As noted in the other answer, it could be motor mounts or brake rotors. But we will tell you the problem.