One thing to keep in mind is that objects produced and marketed as collectibles are, pretty much by definition, not actually rare and valuable. Coin collectors who want them will, y’know, just buy them, at retail, as they come out. The “limited runs” might increase in value as new collectors or collectors who expand their interests come into the market, and they are no longer available at retail. But for “collectibles”, genuine collectors who would be willing to pay a premium are usually swamped by speculators and naive investors, and the supply of purpose-produced collectibles is usually in excess of the actual demand by genuine collectors.
For something as durable as a purpose-produced collectible coin, at best it’s likely to be decades before you start seeing a genuine increase in value due to collector demand outstripping supply, if it ever happens at all.
The items that become rare and valuable collector’s items are usually ephemera that didn’t seem collectible at the time they were originally retailed.