Make your own. It costs me about $.09 a round to make 9mm and 38spl.

Have been reloading pistol ammo since the mid 1970's. Will save you many dollars over the decades if you want to shoot a lot for minimum cost. Good recipe for your 1911a12 pistol: 200 grain cast lead / swaged lead semi-wadcutter-----7.0 grains of unique powder----winchester large pistol standard primer------whatever brand of .45 acp brass you have available to reload.

If you can't reload:
Winchester White box or the Wal-Mart Federal. My Springfield 1911 shoots them both quite well. I've used the UMC stuff in .38 spec, maybe a bit dirty (opinions vary), But surprisingly accurate as well. Worth a look.
I reload, but I occasionally will augment my supply of brass with cheapo ammo.