>>8776439I believe there's several reasons.
1. Digimon is a small, diehard fanbase full of people willing to pay actual hundreds of dollars for tiny LCD toys and 100 yen gachapon figures to get that nostalgia high. Most newer products have small production runs, are marketed as 'premium' items, and need to be imported from overseas which makes the western prices even worse.
2. The franchise has been getting more traction in the public eye lately, so older items are getting hiked up exponentially. I've noticed the average listing price of old cards, figures, vpets and games roughly triple in the last two years. Up until recently I was buying old Digimon booster boxes to open for $100 or even less if I made a lucky find. Now auctions for them are ending in the thousands of dollars.
3. The Pokemon scalper/investor mentality that exploded since 2020 has seeped into every other card game. That means even people who don't actually give a shit about the franchise are looking for any product they can flip and buying out local game stores, clearing the shelves at Target, etc. Even game stores are selling the products that just released yesterday for twice their intended value and selling out.
I firmly believe the western fanbase for Digimon isn't big enough for this kind of interest to have occurred naturally. Looking at Digimon TCG groups, it's almost entirely new users with little interest in Digimon trying to flip overpriced product and barely anyone actually talking about playing or collecting.
4. Most of the very expensive figures and vpets are predicated on pre-orders. Successful scalpers aren't hurt by spending money on large quantities of items that won't pay out immediately, and with Digimon you're basically guaranteed than any limited item can only appreciate in value.
The English 20th vpets are seemingly the only item free from "Digimon Tax" because they were produced in such large quantities that stores are heavily discounting them.