Over the last 5-10 years or so, I've been surprised at how low many Jackie signed items went. 1947 team signed baseballs sometimes went as low $2500. I was able to get a Negro League signed baseball by Jackie and some others for under $2000. It was fairly faded, but still... And signed yearbooks from Jackie's high school and Junior College days (1935-1939) sell for way less than I would have assumed.
Edit: On the yearbooks, I see that a 1939 Pasadena Junior High yearbook 2x signed by Jackie recently sold on eBay for $7250. That's arguably still really cheap for an item he signed 8 years before he made the Majors signed twice, and in one case including an inscription, but a big jump from past sales. It looks like a lot of Jackie yearbooks (mostly unsigned) have sold recently and prices have increased across the board on them.
https://www.ebay.com/itm/JACKIE-ROBI...p2047675.l2557
Even recently, I think things have been up and down. From a buyer perspective, I'm hoping that things settle so I can afford to add to the collection. As someone who loves the history and thinks it should be better appreciated, the recent bump has been welcome.