Market Demand and Pop Culture Influence Media exposure (movies, games, memes) and celebrity endorsements can also impact the price of valuable Pokmon cards
I cast a turn-one Telepathy, and the new player scooped his cards up and left, saying I dont play against Telepathy, it just reveals everyones game plan and then another player can backseat game once they see someone has a victory cinched up. He proceeded to walk away for five minutes, then returned and backseat-gamed us until he saw a winning hand
Three main factors determine value: rarity (Secret Rare, 1st Edition, etc.), condition (graded on a 1-10 scale where PSA 10 is flawless), and demand (popularity of the Pokmon and competitive playability)
Whereever you're buying these, just note the value may continue to rise, or crash unexpectedly
With interesting mechanics, both new and old
Some playgroups or game stores dont like specific cards, either banning them outright or classifying decks with them in a specific category to avoid pubstomping