iPhone back glass AND camera lens replacement?

I have had my iPhone 4 for close to a year, and dropped my phone and have a small crack in the back glass to the upper-right of the camera. I hear that Apple will replace the back glass at an Apple Store, but does anyone know the actual cost? Also, my camera lens got so scratched that I am unable to take clear pictures. Does anyone know if Apple will, or can, replace the camera lens when they replace my back glass? And will that cost extra? Thanks!