Note: this probably doesnt apply to the higher-end chase cards from mid-modern sets, which I imagine are still fairly liquid (though still less so than ultra-modern chase cards!)
It would have been a non-speculative buy for people with organic interest in card history

Sort Card Type Shelgon #48Uncommon $0.45 Shelgon #45Uncommon $1.24 Shelgon #39Uncommon $0.65 Shelgon #64Uncommon $0.51 Shelgon #50Uncommon $1.96 Shelgon #7Holo Rare $1.80 Shelgon #63Uncommon $0.49 Shelgon #56Uncommon $0.22 Shelgon #105Uncommon $8.52 Shelgon #43Uncommon $1.86 Shelgon #108Uncommon $0.18 Shelgon #113Common $0.17 Shelgon #71Common $0.10 Shelgon #44Common $0.41 Shelgon #64Common $4.93 Shelgon #44Uncommon $2.43 Shelgon #46Uncommon $5.00 Shelgon - 053/113 (Delta Species) #53Uncommon $1.47 Shelgon - 054/113 (Delta Species) #54Uncommon $2.76 Shelgon - 20/97 #20Rare $1.44 Shelgon - 41/97 #41Uncommon $3.51 Shelgon - 42/97 #42Uncommon $1.85 Shelgon (Delta Species) #38Uncommon $2.51 Shelgon #105Uncommon $8.52 Shelgon #46Uncommon $5.00 Shelgon #64Common $4.93 Shelgon - 41/97 #41Uncommon $3.51 Shelgon - 054/113 (Delta Species) #54Uncommon $2.76 Shelgon (Delta Species) #38Uncommon $2.51 Shelgon #44Uncommon $2.43 Shelgon #50Uncommon $1.96 Shelgon #43Uncommon $1.86 Shelgon - 42/97 #42Uncommon $1.85

Cyclizar If Roaring Moon left you blurry-eyed, the first secret rare on our list and full-art illustration rare is Cyclizar, showing four of the nightmarish Pokemon stationary at a parking lot next to a sidewalk with some chatting and another sleeping
Once you start swingin with your Faeries, Alela lets you goad a creature if you deal combat damage to a player
Here a Smudges Thin stamp that was found on a Red Cheeks Pikachu by @megacon : (Here again a comparison picture with a Thick stamp