John,
I got/get most of my Osage from Missouri. My in-laws lived there and my father in-law always got permission from locals for me to harvest the Osage when we visited. Since they died, I go to Mo-Jam every three or four years and trade for Osage and other bow wood. Over the years, I managed to acquire a decent supply of bow wood, mostly Osage, but not good enough quality to sell. If I need a good stave, I find somebody on here to trade or buy it. Mark deals with lots of people and manages to maintain a good supply of bow wood on hand. He did go with me the last time I went to Mo Jam and got some there.
If you have a source for yew in Oregon, stock up. Not only is it good bow wood, it is great bartering material, you can usually trade a yew stave for two or three Osage staves.