Cost. Clients need to know. Designers, too.
One client might think a designer is stalling by not offering an immediate quote, as if the designer wants to figure out how much is available. But the designer is by no means guaranteed the business, and it makes more sense to offer a quote as soon as possible.
Thing is, no project is the same, and every client differs, so generally a designer can’t provide an accurate quote until the design brief is in place, and that doesn’t tend to happen until after discussions.
This design pricing formula does a little to explain the complexity of cost.
Update: 23 March 2011
If you’re a design student or a self-employed designer, here’s a collection of resources that might help: Advice for design students.
Update: January 2013
If you want to know more about design pricing, download the “Pricing your work” chapter for free from my new book: Work for Money, Design for Love.