Here is a link to a great price on vellum paper. I don't know the shipping cost but it's sent UPS ground. Even with shipping the price is great for vellum. I also use the thin deli paper sold at Sam's Club. It's dirt cheap but mostly I use that for foundation piecing as it won't go through my printer.
http://www.paperplus.com/productdeta...p?bvn=10016356