I never do it for free, never. Most of my enchants I just ask for a tip, but for the bigger stuff (+81 Healing, +40 Spell, Mongoose, Soulfire, ect) I charge 25g with their mats. No questions asked. If they don't like it, try finding someone else on my server with Soulfire at 10am. Good f***ing luck.

I also charge up the ass for twinks. If they got 4k gold to drop on a level 19 then they can spare a bit more ^.^