I found some at Echter's. :-)

I recently discovered that there is a black raspberry variety bred for our climate. It is called Niwot. It was obviously bred near Longmont. I couldn't find them anywhere as they were all sold out. I was driving home to loveland from Grand Junction and stopped at Harlaquins Gardens in Boulder and found one. They had 5 on friday. When I bought mine on Sunday thethere were two left. Might be one left if you are lucky.

Harlequin and Echter's have good plants in my experience. The Tree Farm abuses plants and sells them for high prices.

O'Tooles on Federal and Belleview has had boysenberries for a few weeks.

@keen101, Our neighbors have black raspberries that they call blackcaps, and they thrive in my SW Idaho climate. They even lived through -21° F. a few years ago. Have you tried those before? They produce a lot of fruit in June and maybe early July (but not the rest of the season). The seeds are more significant than those of blackberries and raspberries (but they taste really good, like soda pop or something). They reseed easily around here, too. When the fruit gets ripe, I might be able to save some seeds for you, if you're interested (our neighbors said that we can pick the berries that are on our side of the fence), but remind me late this month or I might forget. I actually have some seeds that I saved previously, but they're a few years old.

If it were up to me, we'd have loads of them growing in our yard, too (but it's not up to me). We've had them seed into our yard (and unfortunately have had to dig them up).

Here's the Wikipedia article about blackcaps (although I'm not 100% sure whether my neighbors' bushes are this species): https://en.wikipedia.org/wiki/Rubus_occidentalis