The "using the psitol to fight your way back to a rifle" theory is nice, but, based on real world experience, its not going to happen. When the flag drops, you are likely going to have to fight with what you have with you.
There have been a few times I got out on something that seemed pretty mundane that went to poop. And, all I could do was look back at my car and see the flash hider of my AR sticking up between the seats, mocking me.
I think the current theory of "designer ammo" at over a buck a round is ridiculous. 20 round boxes are a joke. If you can find the 50 round LE boxes at a decent price, buy all you can. Shoot a few hundred rounds of that ammo in your gun and accept, its as good as its going to get.
But, I'm not convinced that the most expensive ammo is the best. If there were truly one round that works better than all the others, every LE agency would be buying that round. The Speer Gold Dot may be the most common round in LE right now based on effectiveness and cost. So, I usually just buy that in whatever caliber I need.