I can build a really nice 215 cab for ~ $500 to $600.
Even better, I can build it oversized and internally reduce volume to help tune it to the room..
If I were planning to gig with it, I'd absolutely buy something off the shelf, but I'm not. It's going to sit I'm the studio. Building it oversized also allows me to change drivers as frequently as I want. Reducing airspace is is essy.
Curious why the choice of 215 for the studio...