Very simple: $75 an hour. If you are over 25 miles from Dover, I add 1 hour travel time.
The majority of problems can be fixed in the first hour.  To put this in perspective:  if you call around, you'll find that for a home visit from Best Buy's Geek Squad will run you well over $200, most other places charge from $65 to $100 per hour from the minute they walk out the door 40 miles away until they sit back down at their desk after the visit.

I GUARANTEE: If I can't fix it, you pay nothing (not even the travel fee if you are far away), with the following exception: When there is a hardware issue that cannot be resolved without replacement parts, there will be a $45 diagnosis fee.