Tim,
Head bolts through mail order sources (FastLane, Wholesale Parts, etc) are much cheaper. I got mine (for my impending OM603 head gasket job) for $1.80-$2.20 each. Rather than dink around with measuring all the bolts, or taking a chance on marginal ones, I ordered all of them - cost about $50 but I figure that's relatively cheap insurance, since I don't EVER want to do this job again!
Regards,