If you give the DVD, its almost silly to charge for prints. They could take the DVD to costco, walmart, or even their own printer. Understandably, your process of proofing printing and color matching etc etc may be different and better than an automated photo lab, but you cant really expect any customer to know or even appreciate this difference. Either give prints, or give DVD with free proofs or something. Figure out the line that, for you, is just barely enough money to not be a complete waste of time, and start prices from there.