Halequins Gardens is the best native and drought tolerant plants selection I found in a Boulder nursery. It has a great selection of Xeriscape plants sold by very knowledge gardeners. They also have a nice display garden and a pretty decent rock garden selection. I have been gardening in the Boulder area for years and never knew about this place and I was missing out. It is off a side road on 28th in North Boulder see their website below for directions. They also have a nice online plant list so you can see if they have what you want before you go.