i assume carol doak's paper is a fine product, but it's quite expensive. 8.5 cents per sheet.
i bought children's doodle pads (made from blank newsprint) to see how they'd work. they're great for paper piecing and are only a hair more than 4 cents a sheet after sales tax.
i just found a website that sells rolls of newsprint and bundles of blanks sheets. 2,400 sheets, 15" x 20" for under $25, plus shipping (to my zip code, just under $24, total, just under $58 ). rolls, 12" x 1,695' are under $12, plus shipping. so cost per sheet is around 2 cents. that bundle would probably last me the rest of my life.
http://www.packagingsupplies.com/Newsprint.html
regular paper (normally 20lb) will work, too, but is a bit harder to tear away. if you're shopping for something, look for paper that is 15lbs or less and it will work just fine. look in office supply catalogs. a lot of the pinfed computer paper is lightweight. one pack or case will last for ages. i've been working out of a case i bought years ago.