Here's a short documentary about some folks who bought 60,000 movie ad printing blocks for $2000, a collection now for sale and valued between $8 and $12 million. I saw a Blade Runner block so it's possible there's one for Raiders.
Shortly after the industry switched from plates to ad slicks, which I suppose are also collectible because people will collect anything. People don't turn to the newspaper for movie times so much anymore, and I assume newspapers like the LA Times which still run a lot of movie ads get the graphics straight from the studio or theater. The slicks I found most interesting in the 90s anticipated award nominations and wins which never came. So somewhere there's a whole parallel history of supposedly lauded films told through ad slicks.