This is always an interesting discussion. One great, or two midrange subs.
My philosophy is buy the absolute best one you can now. Then plan on saving for a second one as soon as you can. A lot of ink has been dedicated to single vs multiple subs. I, like most here believe in multiple subs. I currently use three, and two in another system. Two singles in other rooms. All that’s to say, while I believe in multiples, I don’t think you have to go all in at once. Obviously that’s the ideal, but imo bass is an investment, and sometimes investments take a while.