A website with smaller images of the posters for informational purposes would probably fall under the umbrella of fair use. TFN has had a site with all the major posters, but not the more obscure stuff like posters sold in stores, and stuff only available through the original fan club.
http://www.theforce.net/collecting/posters/
I had the posters in the bottom right corner when I was a kid. My color choices with the magic markers might have been a tad off though. đ
Yeah, TFN has an alright selection but itâs certainly not comprehensive and the quality is awful. A site with better information is https://www.cinemasterpieces.com/cinestarwars.htm but their photos are just that, photos. Most posters I have look âscannedâ rather than âphotographedâ.