Better hurry for the CT-40G2 or the CT-9G2 as they are no longer carried in the Taurus catalog.
KelTec makes the Sub-2000 in both 9mm and .40S&W, although the .40S&W is hard to find.
I would not worry about the Highpoint, all of these auto pistol carbines, at the moment, are simple blow backs. The blow back has been around since about WWI and is reliable, although the design causes it to be on the heavy side. You would have to go way up in price scale to get something like the HK MP5 for a modern delayed design.
I have a feeling that with the popularity of these auto pistol round carbines for home defense, as well as the high prices they are commanding at the moment, we will see more modern designs on the market pretty soon. A M3A1 made from plastic instead of sheet metal would be very cheap to make, as would a Sten gun, Swedish K, or any number of WWII submachine gun designs redesigned around modern materials and production methods.