Again, thanks for all of your input. I am a "top seller" on EBAY, but besides my extra Wackys, don't sell WP stuff (I just buy it). I'm a fledgling WP collector, who really wanted to relive that childhood excitement of these stickers (I have very fond memories of the 1982 set with the album). I have no sentimental connection to this poster, so I'll probably try to sell it, and as you say, let the market dictate its value.
Anyhow, thanks again for trying to help me figure out its value.