freitasm: Why wouldn't a photographer give the photos on CD? Afraid customers might get a print somewhere else, taking away some of the revenue?
Partly that, though if the customer pays a proper fee (ie not $150, more like $2000+) that old low up front, expensive prints model isn't really valid.
Mostly, at least for me, it's about the time it takes to get every image ready to print. Think days, not hours. Peoples time is expensive.