It isn't worth the money to ship a head to a machinist and have them do the work, that would probably cost you the price of a kit, not to mention you would get way more performance from a kit or an exhaust.
The savings of doing something like milling a head or porting a stock cylinder come from doing the work yourself. Milling a head down can be done fairly easily with simple tools in your garage or even at your kitchen table (if you are single). There is a great description of how to do it in the wiki pages. Good luck