Sorted by the night you're actually going to. Friday is high school bleachers and a two-hour freeze. Saturday is the campus lot from dawn to a night kick. Sunday is the stadium lot, propane only, into January. Every link opens the product. Check the link for the price.
High school bleachers. Cold metal, no outlet, two hours.
Campus lot at dawn to a night kick. Fourteen hours, fifty people.
Stadium lot. Propane only in most of them. Season runs to January.
These are search links on Amazon, so you'll land on the current listings instead of one that sold out. Heated seats and blankets: read whether the battery ships in the box. Most don't, and the power bank up top runs both.