i agree with IJ. redoing a head is a massive pain the ass. i have redone my own chevy v8"s. i hope to never do it again.
as far as a 7m gots, i had a shop my shop sub-contracts redo my head. deck, magnaflus, valve guides, 1mm oversize intake valves, flow test, the whole freakin 9 yards AND the kitchen sink. cost me $250. what sucked about it is i had to hitch a ride to work for a week straight. but i got a deal cuz of the shop i work at. i also know the machinst from a brother of mine(the two of them hang out a lot!).
550 is a lot to pay, but the labor it takes to make sure that head holds out is well worth the money if you ask me. look around a little more, i bet you can find a slightly cheaper price. but reshiming that head adn doing the all the above is still a pita!!!