Profiles in History auctioned some vintage silk-screened posters yesterday to BIG bids. These weren't even A-level posters, but they sold for some A-level prices:
Monorail (2nd version): $2250
Matterhorn (two sleds): $1700
Skyway: $4000 (WOW!!!!!)
Golden Horseshoe: $1200
Inner Space: $1200
Grand Canyon Diorama (2nd version): $3750 (WOW!!!!!!)
Alice (no Fantasyland): $1400
Flight to the Moon (NOT the TWA one): $2250
Space Station X-1: $2750 (WOW!)
And these prices don't include tax or buyer's premium, which could add as much as 25% to the total.
If you have any of these (I have some...wish I had more), congrats!