Never heard of or ever thought of spray basting with hair spray. This thread started out with a comment about the cost of spray baste. I have been spray basting for about 7 or 8 years and won't go back. But I have discovered that I don't need to spray as heavy as one would think to get the same "sticking power" I get at least four lap/twin quilts from a can of "Spray-n-Bond" that I get at JoAnn's when it is on sale. So my cost is then about $1.50 or less per quilt.
I have some cans of "The Original Quilt Basting Spray" made by Sullivans that works well but it was donated to me so I don't know the cost. Because of the odor I only use in when I can have the windows open.
Best advise: Watch for sales, coupons and then buy two.