Hey Bruce, I love collecting advertising posters, including travel posters such as early TWA and Air France. You probably don't have available, but it would be great to see, your collection (or part of it) if you have it online
You must have quite an impressive collection! What else do you mostly collect?
I have heard, maybe on this board, and agree, advertising posters tend to stay up on the walls longer than movie posters. Even though I have much more movie posters, I probably deep down prefer the advertising posters mainly because of the (typically) stone litho / bold colors look. I have mentioned previously I rarely watch movies or collect movie posters for any other reason but the art, so this maybe a factor.
Sounds like eBay can't be that bad a place as collecting 250 travel posters (which are much less numerous than movie posters) in a short space of time would indicate to me eBay is still a great source of posters, especially if each were obtained with just a few minutes searching! But, please, leave some there for the rest of us