made that mistake when I started out years ago. Find out what others charge for the same service then bill accordingly. Dunno about how others feel but I had a "If I cant fix it, no charge to the customer" Policy. Didnt cost me much but got me a solid rep fast. Havnt done desktop in a while so dont have the skinny on the best tools for that.
Sorry to hear you are not working, hope this works out for you
thanx,
bill