Elderberry cultivar plant sources?

Does anyone have or know of Elderberry Cultivars Plants for sale other than Richters Herbs? Sourcing the native plants is easily done through conservation authority and native plant nurseries. A few years ago I got a few Samdal and Samyl plants from Nourse through Strawberry Tyme - they did very poorly. I would like to grow and compare a variety of Elderberry types.

Have you tried Wiffletree?

Check Green Barn Nursery in Quebec, a bit far from you but they can ship:

https://www.greenbarnnursery.ca/products/adams-elderberry

I’m trying Lareault Nursery in Quebec for my strawberries and low use blueberries. I’ve noticed they carry some elderberry as well, not sure which cultivars.
PIne Needle Nursery in Pontypool not far from me has elderberry…more or less the wild cultivar for naturalization…Sambucus Canadensis
Cheap way to play around with a bunch. Under 2$ for a year seedling, but you have to buy them in a 25 plant bunch…

Thanks for all the suggestions. I appreciate the info. I will have 3 new varieties to plant this spring.