Don't need to have shot a 45 GAP to know I don't want to pay nearly 50 cents per practice round for one. I don't even own a 45 ACP due to ammo costs, but I'd get that before the GAP because it's significantly cheaper to shoot than the GAP.
That has not been my experience. I have guns in both .45 acp and .45 gap, and I buy in bulk from Natchez Shooter's Supply and Georgia Arms.
In both of those cases, some loads are the same price as a.c.p, and in others, about 10% more. But , whether .45 acp or .45 g.a.p., it's still about $.50 a shot -- shooting .45 isn't cheap.
Buying locally CAN be a problem, but I seldom do that -- local prices are just too high.
The Glock 38 I shoot is the first .45 that I really enjoy shooting; it seems as soft-shooting as a 9mm, to me.