Re: Good source for jos?
If you can find dowels of hickory, black locust jotoba - I'd go for that! I know a maker of really great hickory or jotoba jo, which cost $60, IIRC. Don't know how much business he wants, so if you are interested, PM me.
But if you can find such dowels, that'd be great. Black locust is actually a good possibility, as it's being increasingly marketed. Never seen hickory or jotoba dowels.