<humor type="sarcasm" seriousness="15%">
In the spirit of High School Physics:
1. Conduct Experiment;
2. Determine Result;
3. Fudge Data.
you might try
1. Determine what customer wants to, or is able to, pay;
2. Divide that by how many hours you think it will take;
3. This equals your hourly rate.
</humor>