Purchase on “Wheel of Fortune” … or every other letter of this puzzle’s grid

VOWEL

["Think of the letters you can’t buy in a typical word game—they’re often the ones that help you solve the puzzle first. This one’s a key part of almost every English word."]

This clue plays on two meanings of "purchase" on Wheel of Fortune—the game show where contestants buy vowels to solve puzzles. The second half hints at the answer by noting that if you take every other letter of the grid (assuming it spells "V O W E L" with filler letters), you’ll spell out "VOWEL." It’s a clever double reference to both the show’s mechanics and a hidden pattern in the puzzle itself.