Adorama is offering $4.95 16x20 prints right now. You can get them on Kodak Endura Matte, Endura Lustre, and Metallic papers. That's at least 50% off - the Kodak Metallic prints are normally $14.95. I've never ordered prints from them before, and I know nothing about Kodak paper, but geez, it's Adorama. I'm sure they're great. I plan to try out the metallic paper; report forthcoming.
Plus, you get 25 free 4x6 prints and 3GB of storage when you sign up with them. Actually, pretty much every place gives you free 4x6s for signing up. I'll bet if you just kept on signing up for these places, you could get free 4x6 prints for life.