Budget friendly is a relative term. Give us your budget.
That said, the only budget friendly captain's chairs are in a salvage yard and hard to find. Also, they likely won't be in great shape. There are really no modern 'new' aftermarket van seats that are budget friendly, if your budget is anything like mine.
Expect to pay at least a few hundred per seat for anything worth having.
2010 Chevy AWD home build