Q.Will Chokecherries Grow In NW Wa
If so-sources
Certified GKH Gardening Expert
They will grow, but not as well as they could. Zone 8 is slightly out of their range, as it does not stay cold enough for long enough in your area to suit their chill hour needs. This will inhibit flowering and fruiting, mainly. Likely, it will grow and leaf out, still. You aren't so far out of their zone that it would fail to break dormancy.
I would opt for cherries with low chill hours. This article will offer more information:
https://www.gardeningknowhow.com/edible/fruits/cherry/chill-hours-for-cherries.htm
As far as where to purchase- We do not offer that information, unfortunately. I would say to check your local sources, though. They would have more of a selection that is suitable for your area.