Have you considered selling these on eBay? I sold some movie memorabilia a few years ago and the bidders from overseas paid very well.

or

Maybe look into this site:
http://www.filmscoremonthly.com

And check the different forum boards. These guys are gonzo film score collectors and you've got some posters representing John Williams, James Horner, Howard Shore and Mark Snow. It is a different marketing angle ;)