I had my balancer replaced at a cost of about $250 dollars.
The removal and installation was pretty straight forward. But it was a chore to get off... but if you've got the right tools anything is do-able. I think the part cost around $65.
It's been a while so I may be a little off on the costs... but I'm sure the service charge for parts and labor is correct.
$750 is a lot of money... too much.
Find yourself a decent local mechanic that deals with foreign autos and give him a go... it may end up saving you a lot of scratch.