It is true that you could probably do it yourself, but you have to keep something things in mind.
1) Like Embraced said, measure three times, drill once
2) You want to use a drill bit that is the same diameter as in the core of the screw
3) You need to know the exact depth you can drill to - deep enough for the screw length without gettiing to the ptex on the other side
4) Go ahead, measure again.
5) First try on a junk pair of skis
6) I still think it is worth the $50, though it is a ridiculous rip off. Mine shop charged me $65 recently and I couldnt believe it. The previous cost I paid was $25.