What are the odds of pulling a specific card?

Take the pull rate for the card's rarity and divide it by how many cards share that rarity. Example with live data: Charizard ex #199 is a Special Illustration Rare from 151. That rarity appeared in 3.11% of packs in the cited sample, and the set has 7 Special Illustration Rare cards, so the odds are about 0.444% per pack (about 1 in 225).

Over 36 packs that's roughly a 14.8% chance of at least one copy. Its current market price is $323.37. This assumes every card within a rarity is equally likely, which the source supports as an approximation. Try other cards in the simulator.