I've always wanted a 2011, and have been intrigued by the 9x23 Win cartridge as it seems to make the most out of the 2011 frame, but it seems that I can't find anyone making these anymore. Are there companies still making them? TIA

We were discussing that on a 1911 forum a couple of weeks ago. No one can remember any pistols being made in that chambering except the initial batch Colt did up.

Several wondered why no one else has made any pistols in that chambering, like Les Baer or some other worthy maker. It IS what the Super COULD be, should someone load it to the gills. Most of the discussion centered on the pressures involved, and the liabilities of those pressures.
Overall, we decided that it was probably smarter that no one did develop it further, as the liabilities outweighed the positives, especially when the .357 SIG is out there.

I know STI used to make them, but I'm having a hard time finding ANY 9x23s let alone 2011s, even STIs. I'd like a production gun, but if there is a custom builder than can make them work that'd be okay as well.

I would look at 9x22. Double Tap or Underwood 125gr loadings have Vo of about 1450fps. Sig Sauer used to offer one. It is or was external extractor gun with rounded butt called beast or monster?

I'm not interested in 357 Sig, my interest is in the 9x23 Win in a 2011. I know they used to make them, but I cannot figure out why they stopped, as the 9x23 Win seems like a much better way to create a fast nine over the 357 Sig.

Ratsmacker smacked it.

The 9x23 and similar were developed as a competition/gaming cartridge. The push was for a cartridge that made Major and created enough combustion gas to take full advantage of a compensator. The 9x18, .38 Super, etc. loaded to Major created pressure problems. IPSC lowered the Major threshold from 175 to 165 which put the 9x18 and Super back in the game and effectively killed the 9x23.