modern league leaders cards

[abothebear]

My nephew loves collecting cards, but he hasn't seem to develop any sense of the players, history, or market of them. Yet he is always asking me if this or that ebay auction is a good deal (it never is), or talking about how a card he scanned with an app says it is $600 (it never is).
I think I am going to suggest to him that he try to focus on a couple of projects. My latest idea is that he might try to collect all the 1968 league leader cards so that he'll develop a sense of who the star players of that time were. Simultaneously, he could put together a modern league leaders set so he can get an idea of the current stars. And after completing those, he can add others from different time periods. The mini leaders from the 80s would be fun but would take all of two minutes to "collect".

What would be an inexpensive but not too easy league leaders set to collect? I don't know much about modern stuff. Does 2024 Topps Chrome have league leaders? What is the deal with the chrome sapphire cards? what is a reasonable price for a league leaders chrome sapphire card? I can't make sense of the ebay listings.

Thanks!
George
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