So, how much is a 39 year old Aaron Rodgers worth to trade?

At his age, I would say a 2022 1st, a 2023 3rd that could become a 2nd or 1st based on team success thresholds (like advancing to the Divisional Round, Championship Round, and/or Super Bowl, along with maybe a random non-star player.

I think you could expect a solid three year run out of him; to me, that's worth the risk, especially if you're Sean Payton and your career is (seemingly) winding down.