As has been suggested, the 10mm Auto really comes alive when you handload for it, and in that respect, it really isn't any more expensive or difficult to find than the .45 ACP. The brass costs about the same and you buy it off the internet in the same places. The 10mm uses the same readily available projectiles as the .40 S&W, though I would suggest you stick to bullets of 180 gr or higher for most uses. I think that is where you get most of the advantage of the 10mm Auto. For all around use, it's hard to beat a good 180 gr JHP @ 1250 to 1350 fps.
That being said, it isn't all that difficult to find 10mm Auto on store shelves around here. If you keep your eyes open, you'll see a few boxes of factory fodder, usually 175 gr Silvertips, laying around. The Silvertips are a good medium load and are what is available, so that is what I have in my Gen III G20 right now.
For factory ammo, I actually prefer Double Tap. Mike McNett loads some good stuff. He used to load a 180 gr Speer GDHP @ around 1300 fps. That load was outstanding, but I think he was forced to drop the Gold Dot. Still, the internet is the place to find 10mm Auto ammo. And Double Tap is among the better places to do it.
I got a Glock 20 originally more out of interest in the 10mm Auto and actually grew quite fond of both the Glock and the 10mm. The Glock 20 is among the more available models out there chambered for the 10mm Auto. Mags and accessories are easy to find, and the Glock offers you the option of buying a replacement .40 S&W barrel for cheaper practice. The G20 has proven durable over years of use and thousands of rounds of the hottest SAAMI spec ammo on the market, and may be one of the only pistols ever chambered in the round that has never had any real durability problems. It is large and doesn't fit everybody, but if it works for you, it is rock solid and 15+1 rounds standard capacity of full power 10mm Auto is about as much firepower as you can fit in a handgun. It makes an awesome trail gun. If you're not going to handload, a G20 should be go-to-go out of the box. If you are going to handload, I might suggest a KKM or Lonewolf barrel and a stainless guide rod with a 20 pound spring. The Glock barrel is well made and perfectly safe for any SAAMI spec ammo, but it does have a slightly looser chamber than the KKM Precision I put in mine. This can negatively affect case life. So to preserve cases, an aftermarket barrel helps and is worth the investment. Also, the factory 17 pound recoil spring tends to launch brass into low orbit. This, again, is of little consequence unless you reload. If you want to find your brass and maybe smooth things out a little bit, a SS guide rod with a 20 pound ISMI spring is about $40 and well worth it.
But yeah, the 10mm Auto is an excellent cartridge with unmatched versatility in the auto pistol world. While it will probably never be mainstream, it has a dedicated loyal following and has survived for decades after it was declared dead. I think it is with us to stay for a while. And it has made it thus far on its performance, not big name brand advertising or nostalgia like the others.
Here's my fist full of rock and roll:
