Raddad,
Just bought a bunch of 7/16" OSB at just under $6.00 for a 4x8 sheet and it was about $2.00 cheaper than drywall.
My heated pole barn has OSB on the ceiling and the joists are covered with 6 mil clear plastic. This keeps the air from migrating to the attic as well as acts as a moisture barrier. I have 14 inches of blow in insulation above the plastic. Seems to work fine for me. Wish I had painted it white prior to filling the building.
I agree with the drywall being finished and painted being better at keeping dust form adhering in a wood shop. I did not want to finish the drywall if I had used that, finishing is not one of my strong points.
David B
