Some of the problems I see are that: (1) condition is a huge part of a chip's value (both sides), so someone would have to scan both sides to be able to value the chip (with the app being able to give comparative prices), (2) most cell phone, etc. cameras do not have that great resolution, so it would be hard for the app to make a definitive evaluation, and (3) some chips look the same, but can be quite different in value. Could the app pick it up? Example:

One is worth quite a bit more than the other.

I think it's a great idea, but I don't know if it can be pulled off. Good luck.