Yes, Allen's website (cochips.com) is useful for research and values, but ...
I've found that he prices the scarce/rare/key chips much higher than they should be (IMO).

But for relative values, it helps sort out the more valuable chips from the common ones. He also give quantities issued, which helps with determining the rare / hard-to-find ones.

The overall problem is that demand for Colorado chips is much less than at the peak, early years.