It's relative to what you buy in total. Last time I bought ammo it was 9mm. I split a case of Speer lawman 9mm from Natchez, paid about $.23 per round. And I added a few boxes of .45 auto as well one box was Fiocci jhp at a little less than $20 a box. Not the best HD ammo but good enough for me to sample it at the range. I'm still try different ammo in my 1911 so I buy a lot of different grain/brands.
SIG 1911 .45 ACP
SIG P229R E2 SRT 9mm
Beretta BU9 Nano 9mm
Beretta 84FS .380 ACP
PWS (Primary Weapons Systems) MK114 5.56 NATO