I charge $75/hr, 2 hr minnimum. Time starts when I start setting up (my Lucas sets up in 15 minutes or less) It'll cost $30 if I hit metal that simply requires me to solder new tips on, $275 to replace a ruined blade (I've only ruined one so far, and I'm ashamed to say the log was mine) That said I scan for metal and foreign objects visually first, and with a handheld metal detector. If I detect metal I'll still offer to saw the customers log, sometimes after making an effort to cut out the metal with a chainsaw, and failing that, if the log is large enough, by trying to avoid the location of the metal.
I also charge for mileage there and back at .50/mile (which given the current trend in fuel prices may need to be increased soon)