I agree that there are few units in CO that don't produce 180" bucks, but like Founder said,you can hunt low, high, or REaLLy high! In their Winter '12 edition, Western Hunter magazine did a good article on Boone & Crockett entries over the last 10 years, and had 6 CO counties that fell in the Top 10 in N. America:
Eagle- 27
La Plata- 18
Montezuma- 17
Garfield- 17
Gunnison- 17
Mesa- 17
I would get an overlay map of the counties and the GMU's, and start looking at the terrain you want, and the pricing you like. As has been said, there are a few brokers that you can use to find tags/pricing and figure out what would work for you.