Just get some crab apple! That's what I did when I lived in Boulder. Crabapple is everywhere and it is a good bow wood. Most people just let it grow crazy, so you can convince just about anyone to prune a limb or two. You can also talk to some apple or plumb orchards and see if they have some cuttings that you could billet. Check craigslist for people selling plum, apple or walnut firewood and you can probably get some billets if you dig through a pile. I went up outside the mountains around Lyons (Jamestown if I remember right) to get Rocky Mountain Juniper. You can just talk to some folks if it is alright to cut one or take some limbs off an old one if you find one. It is great wood and really beautiful and rewarding to work with. There is Black Locust there, but where I am not certain. Also, you could try looking for some compression pine if you know how to work with sinew to back it. Rocky Mountain Specialty Gear sells staves also...not cheap, but at least you can inspect them first.