took my 92 subaru legacy auto turbo into a mechanic for warrent he said the rear transmission mounts were broken, anyone know what this would cost to fix and if its worth it? also can l drive around for long periods like this?

cheers

l would get it fixed.
You have driven for who knows how long it has been broken, so if you do not punch the throttle a lot your drives should be alright.
As for the part, which will be hard to find, it appears that it will have to come from the dealer or salvage yard or e-bay motors. At the tune of about 70 dollars each (e-bay) to most likely double that at the dealers.
Labor costs will be the problem, my guess it two hours of shop time.