Olympic Arms is closing shop. They had a nice little 10mm AR that used proprietary 18 round mags for $1,000 or so. I was contemplating getting their 10mm flat top upper & mating it with a Spike's Tactical Pirate lower (because Arrrr-15), and were it not for Governor Bloomberg's damned magazine capacity ban I may have done so already. Did I mention Bloomberg, Hickenlooper, et al can go to hell?
Feather USA made a nice little 10mm carbine that ran off of glock mags. I'm unsure what their situation is now, but they have a notice up that they aren't accepting any new orders or quoting prices on rifles.
Thureon Defense has some 10mm carbine options. They run on glock mags and start at just under a grand.
The Aero Survival Rifle also runs on glock mags and can be had in 10mm for a little over $800.
I've mentioned this before, but if you send a Ruger GP100 in .357 magnum & about $650 to Clements Custom Guns, he'll send you back a 10mm GP100 with 10 moon clips. Add another 2 bills and the action will be smoothed up.
Ranger Point Precision will work similar magic, only the recipe involves sending them a Marlin 1894 lever gun in .32-20 or .357 magnum and about $1250 to get a 10mm lever action carbine
The Kriss Vector Gen II CBR runs on glock mags and can be had in 10mm for $1500 or so.
Mec Tech Carbine Conversion Units are available for glock & 1911's for just under $500 each. The downside is they're straight blowback so they advise to not use "hotter" loads than +P.
Sig Sauer offers their P220 Hunter in 10mm. It's a single action with a 5" barrel, 8 round magazine and a $1600+ price tag.
While there are some choices for a carbine in 10mm I'm not particularly thrilled with them (though the10mm lever gun is a neat idea). Too much plastic for my tastes. I'd like a simple little 10mm carbine that could be stocked in walnut or a nice laminate. Also, most of the offerings seem to be straight blowback, which could limit the loads you could use. Some sort of locking bolt or even a delayed blowback would be nice. It'd also be nice if I could find one that ran off Tanfoglio mags instead of glocks.
A beefed up Ruger 10/22 or M1 Carbine, or a Marlin Camp Carbine, or something as simple as a semi-auto-only Sten would likely sell well if kept in the $500 range. Use some sort of dual extractor system where the headspace isn't on the case mouth thus letting .40 S&W be run in the same gun and I think a lot of folks would just have to have one.
The Clement conversion of a GP100 is very tempting, and the Sig looks nice if too damned pricey (in fairness it's not much more than the cost of a GP100 and a Clement conversion). There are a few 1911's in 10mm out there (I hear Colt is adding a railed Delta Elite this year), and of course the plastic brick (i.e. glock) but I'm still of the mind that the best bang for buck in a 10mm is the Tanfoglio steel framed platform, marketed over here as the Witness by EAA. That link will show they offer 13 models in 10mm, 11 of which have steel frames (as the Good Lord intended) with MSRP's ranging from $650-ish to $2400.
It'd be nice to have a compact single stack, like a Kahr K40 but in 10mm (and preferably with a hammer, cause Murica) or a Remington R51 in 10mm sans bugs. It'd also be nice if Katheryn Winnick returned my calls...
The 10mm certainly isn't dead. Methinks that the overall increase in ammo prices helped, as 10mm cartridges aren't as relatively expensive as they used to be (though 34 cents a round for the weak stuff ain't exactly cheap, and Buffalo Bore's hot 180 grainers run $1.50-ish a pop). Despite a couple of models disappearing there are some nice new options for folks wanting to get their centimeter on, but I'm still not seeing a carbine option that really speaks to me.