Buy the question, not the audience. ChatGPT is the only assistant that sells ad placements, so this is one surface, bought self-serve, and new enough that nobody has priced it properly. Ads reach free and Go plan users only, so the honest test is whether any part of your buyer sits there. Bids allocate budget between questions, and a lifetime cap does not pace, so spend is paced by hand. Not doing: claiming presence across assistants that do not sell ads, or shifting budget out of channels that already work.