https://www.gamespot.com/articles/pokemon-card-prices-are-making-it-tough-to-play/1100-6461778/

I lay restlessly in bed a few nights ago thinking about something I presume many people who have just turned 30 think about: Pokemon cards. I wasn't counting Mareep to lull myself into a slumber, nor was I dreaming of sliding down the freakishly long neck of an Alolan Exeggutor (not tonight, at least). No, I was thinking about how bloody expensive the Pokemon Trading Card Game is, and this made me unreasonably upset at roughly 1 in the morning.

Something you learn about very quickly in the world of Pokemon cards is the meta. Certain decks of 60 cards are just better than others, so if you want to be competitive you need to have one of those decks. It seems simple, but herein lies the inherent problem with The Pokemon Trading Card Game: the best decks have the best cards, and the best cards are often rare (or even ultra rare), which makes pulling them randomly from booster packs extremely unlikely and uneconomical. So unless you're funded by Team Rocket or you can convince someone to trade their very good cards for your not-so-good ones, the next logical step is to find someone selling the cards you need on eBay or through a collectible card seller online. But of course the rare, powerful cards are in high demand and have a premium price tag attached to them.