Don't feel so bad. When we like what we do we tend to charge less cause we sorta think it's easy. I still under bid and been doing this work for a looooooong time. The only way to bid right (IMO) is to let someone more shrewd than you do it. Kind of like how the butt head in the front desk of a auto shop gives the prices and the mechanic does the work. They never seem to under bid do they.