Minor League sets are always a shot in the dark. Even long after their release! A big part of that is team-releases. With only one team in the set, it's hard to get more than one card of a player that eventually makes the set worth anything. Also, those sets are generally overlooked by player-collectors and the team-collectors are keeping everything they get.
Personally, I would focus on All-Star sets for specific Leagues. They are the most likely to contain more than one card of a future star in the MLB. BUT, that still doesn't mean collectors know about them or pay attention to them. For example, I have the 2001 Grandstand Appalachian League All-Stars set. I was the one who added it here on TCDB, along with all of the scans. But most of the hobby still doesn't know about this set! The considered value is still very low just b/c people don't really know about it. It had one of the very first cards of both Yadier Molina and Joe Mauer. But the set still doesn't get much attention.
IF I'm not mistaken, both Dye and Giles have MLB RC cards in the late-90's, so an MiLB card of them from 2000+ wouldn't be worth much at all. Even their MLB RC's aren't worth much. I would guess that even that Nolan Ryan card wouldn't be worth much since it was well after he retired.
If you are looking for value in MiLB sets, I would think that currently they would be early 90's sets that would have players who are now HOFers or possible HOFers in the next few years. Sets from around 2000 would have to contain big stars to garner any kind of attention or value. Since most team-issued MiLB sets only cost $5-10 per set at the ballpark when released (even when made by big companies), they don't sell for much in the aftermarket unless it has major stars. In that case, it's highly unlikely to find a valuable set in a thrift store. That doesn't mean it's impossible though!
If I was going after any sets from the MiLB, I'd go after Gulf Coast League and Appalachian League (as they are the bottom of the MiLB and where most Draft Picks start out) OR any AAA Leagues (the step below MLB and also where injured stars go for rehab assignment)! JMO, but it's a well thought out opinion!
NO PWE's EVER!!! PLZ PM me 1st before sending any offer. ONLY selling cards as of March 2024. No trades or purchases right now.
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Largest total PC card collections by Team, then Athlete (as of 3/22/24):
STL Cardinals (MLB) - 8810; Carolina Panthers - 2888; GB Packers - 1790+ cards
Mark Martin (NASCAR) - 2038 cards; Jimmie Johnson (NASCAR) - 1875 cards; Jeff Gordon (NASCAR) - 1594; Ricky Rudd (NASCAR) - 839; Ozzie Smith (MLB) - 707