Iben, replied to your pm but will post it here as well.
I've never bought a stave and I don't think I've ever seen any around. I have heard rumors that you can get them at Calgary Archery Center and Windsor Plywood (Airdrie location).
You can find some decent boards of maple and likely oak at Windsor Plywood. Stoker mentioned Black Forest and they have a reasonable selection for boards from what I remember. The only staves I've had are chokecherry, saskatoon and a couple of city trees after Calgary drivers generously pushed them over after winter storms.
Can't have a dangerous tree lying in the road...
Pat B - We live in a different world up here! It's either bald prairie or Northern trees - coniferous (but no yew or juniper), birches, and popular family trees dominate. You can find the odd stand of chokecherry and saskatoon though. I was down in SC a couple weeks ago and that got the wood envy meter right cranked...