But as the ES-3 build puts my guitar+bass count at 30, (31 if you include the Harley Benton bass kit to be built next year) I really haven't got room for any more at the moment.
Sounds like you should get to work on an extension for the house!

If you need cases for any of those 31, the AG ones are good value. I've only bought their plywood cases, but I'm sure the ABS ones would be equally on par.