I have a Crary air reel.  One downfall that never seems to come up is that $10,000 price tag you mentioned won't make your head worth $10,000- more next year, maybe $1,000.  I'd recommend looking for a good head that already has one on before I'd buy a new one to install.  At the very least, make sure the head your putting it on is a head you want to have for a while.  Otherwise, the other posts have covered it pretty well.

Good luck,

Mike