Hi Dave,
If it's a one person business, to do a decent job, he'll need the seals + about 2 hours to get it done + oil to fill it up so I'm tempted to say that it's a fair price.
But if your local garage is one who employs a couple of mechanics, someone at a reception desk, someone for spares and someone to do bookkeeping/invoicing, then it's even on the cheap side