Ugh, I feel your pain. I'm 6'1", 170 lbs (17" neck, 35" arms)--am I really such a freakishly sized human being that finding a shirt that fits me should be so difficult? James, I think we should blame the New Fat American Normal for this--most men (in the U.S., anyway) who have your neck/arm size, no matter what it is, ARE probably obese.
The really shite thing is that being skinny dooms one to spending twice as much on every "effing shirt" they buy. It probably is easier to just gain a few hundred pounds. =)