Seems reasonable to me -- current MB list price for each mount is $162.00. It takes roughly 2 hours of labor to replace each one. At say, $90 per hour.

So this would be $324+ in parts and 360+ in labor -->$684 plus supplies and tax. It's in the ballpark of what he quotes.

Not defending dealer pricing or labor costs, but given current pricing on things, it is what it is.

Cheers,
Gerry