It depends on the shop labor rate, to remove and install the forks, you can expect a 2 hour labor rate. Here in the Phoenix area the going rate for shop labor is around $90-95 an hour. It's really not a difficult job to replace the fork seals, the last time I did it about 2 months ago, I think I had both forks done in about an hour and a half, with the forks off the bike already.