Well all depends on your experience, and more importantly if you have the right tools as just a torque wrench aint cheap.
if youv not done one before or at least have someone watching over you I wouldn't recommend it..
as for price, last time I changed my head last yr the gasket, bolt kit cost me 200 but a garage prob charge more..then day or twonlabour so not cheap
pm me if you want it done I see your not to far away, sure we can work something out... beats getting ripped by garage anyways!
forgot to mention, its not that hard changing the gasket the hard part is setting it all back up and getting it running smoothly again! so easy to get your clearances wrong.