Rich Halegua, individually: Best source for original Miramax posters (Pulp Fiction, etc.)
Mid-level dealers - if you can't find the poster at auction or don't want to wait for it and are willing to pay somewhat higher prices (but not rip-off prices):
filmartgallery.com (especially if want a LB poster)
majesticposters.com (best prices for a dealer)
fffmovieposters.com (has outstanding large pics of all posters, from the owner's personal collection, I check this site daily, they're adding 20 posters every day)
kinoart.net (in Germany, but best general source for European posters, site available in
English language)