Where can I buy field points in sizes other then 75, 100, or 125. I'm looking for heavy sizes.

Places that sell mostly compounds won't have 'em. You've got to go to the sites that specialize in traditional archery. Kustom King or 3 Rivers.

http://www.kustom-king.com/
http://www.3riversarchery.com/

Lancasters has pdp points that go up to 145 grains. here is the link
http://www.lancasterarchery.com/shop/default.php?cPath=38_80_77&sort=3a&page=3& amp;osCsid=cf7fac99a707b8bd7264de41e54265ef

I shoot some from 3 rivers archery. 200 grian.