Not sure, but honestly, gluing the blank is fairly easy in comparison to tillering/shaping a bow ...
can be done with innertubes as clamps, or using plain c clamps or metal spring clamps ...
I don't know who sells osage boards ... maybe Mike Yancey at Pine Hollow Longbows ...
He might be able to hook you up with the blank too but dont quote me on it. I vaguely remember him having some or other typoe of pre-glued blank.