Do these things tend to go up or down in value years after you bought it?
Seems to depend on the franchise and rarity.
Some of these turn up dirt cheap 10 - 15£ about a year or so after release. Ashens (youtuber) actually has a show looking at 'ultra rare' limited editions that he picked up super cheap or got gifted by friends that decided that they didn't want a dustcollector after all.
On the other hand you have stuff like Zelda special editions wich usually rise in value (like most nintendo stuff). There was a limited 5000 copies worldwide Zelda Oracle of Ages/Oracle of seasons editions that people try to sell for upwards of 3000$ on ebay. (Not that I have seen any that have actually sold....)