I don't know about an online source, but I know that Crosscut in NW Portland has quite a dowel selection.
I’m building a couple of custum sized stools for weaving. Two for a local weaver and one for my daughter.
They use 1 inch diameter dowels for the rails and the stretchers. Each design uses six 36 in dowels. They use a woven seat and are very ergometric
I’m looking for a mail order souce of high quality hardwood dowels in cherry and hard maple.
I’ve been very happy with the Cincinati Dowel company products but if somebody has another souce I would be interested in checking out another supplier.