You should post this in the
DIY sub-forum more than this one (this one is more general, more about commercially available subs).
Sub boxes tend to work best with the driver they're designed for, particularly ported ones. You can match up a particular driver to a box design using the driver's T/S parameters (Thiele Small parameters) and appropriate software (like winISD). Even the amp might be customized with eq for a particular driver/box combo. This article may help
https://www.audioholics.com/diy-audio/building-a-do-it-yourself-loudspeaker-design/driver-selection. Just popping any old driver of the same diameter isn't likely to produce optimal results; you might try to reverse engineer it if you have the T/S parameters of the original driver.
It might be better to simply get a quality sub driver and build a box designed for it. Parts-express.com has drivers in your price range (and in some cases even a flatpack box can be bundled with them, or flatpacks from the same supplier can be had thru diysoundgroup.com).
This is a design for a sub using a reasonably priced driver, and you can peruse the diy subforum here for other builds.
Doubtful JBL still sells the driver for that particular box but have you asked? What is the make/model of the driver in the box now?