Just had mine done on my 93 GT.
Parts from Toyota were Head gasket kit, head bolts, oil filter, another gasket on the head that wasnt in the kit (I think thermo housing gasket) That all came to £102.00 with my trade discount so probably add 20%-30%
Skimming the head and pressure test to check for leaks/cracks came to £83.00
Labour for me was £30 per hour x 4 hours so £120.00 (Most garages will have a book that tells them how long a job should take and SHOULD book it out to you at that amount of hours, even if it took them longer. Its not your fault their slow if they go over that time.
So all in all im paying about £320. I'd say it would probably be more like £450-£500 if I didnt work at the place I had the work done!
Anything you might want to change in or around the head - now is the time to do it whilst the heads off and the jobs easier!
Garages will differ in price and quality of work so you're best off asking around local garages for prices. If they look dodgy, they probably are going to take the piss. The parts for my head took 3-4 days to order due to being import and bank holiday.
Hope this helps mate.