Hey man, what I did before I started teaching again, was check the local music shops and ask how much their lessons are running and run right around in that range.
You can raise or lower the price all depending on how good you feel your teachin skills are. Also I'd suggest doing payments such as, $XX for 4 lessons, or the per lesson route.
But as far as straight up teaching goes, I'd knock the first couple lessons out with learning to reading tabs, the open chords, and getting him used to strummin and whatnot.
Also find out what his favorite bands are and maybe learn one of those songs to impress him and help him get really pumped up about playing.
I'd either buy a mel bay blank tablature book from a local shop, or just print the blank ones off the internet. I do both.
After that I'd start moving into scales and whatever else.
The only key thing I'd tell ya, is to do it at his pace. Just use your discretion with whatever you teach him, and at how fast you teach him. Don't get too far ahead of him, but stay far enough to challenge him.
You're the teach man! It's easy and real fun.
hope that helped.