I don't live in Boulder County ; and as I hinted my people had "happy feet" . I've chased them all over the country ! "Grammie" (great-great-grandmother Jane (Trimble) Carlton 1849-1942) lived there for 65 years but my side skedadeled after about 10 years. Think I have most of my Boulder work done (of course assuming like that is a guarantee of disaster).
I bought these 3 books about 10 years ago from the Boulder Genealogical Society ; which I believe was handling the sales for Mrs. McRoberts. I think they are still available.
There is also a book of abstracts from the county marriage records that I don't have ; the posts I've seen are very helpful.