That is true eric, so do what I do.
Order your ammo a case at a time from www.ammoman.com
I dont have a 10mm(always wanted one), but I did get 45acp ball from them, and a friend just bought a case of 308 match ammo from the company for his new DPMS Arms 308 M-4 style rifle.
I went the .40 route with my Glock. I was a little apprehensive about the popularity of the round but its become almost as common as .38 Sp. I have a 6 inch blue Python I got in 1970. Its in 95 percent condition. I have pretty much retired it in favor of the semi auto.