Actually, I think I'll do the math for my personal ammo in this context (only because I know what it is and quantities)
A pistol I got last year as the example. This one is 9mm. I have 2,350 rounds through it so far, about 200 of those are premium JHPs to test function and prove similarity to practice rounds....that's a fairly common number of defense ammo people report testing their guns with.
I'll not count shipping right now since that gets complicated, but I'm sure it would be substantially similar if I looked at actual orders and amortized shipping prices.
Good factory FMJ, Speer Lawman, $205/1k. 2,150 rounds of those would be $440. Federal HST $26/50 is $104 for 200. Total, $544 plus shipping.
To go with all WWB 147gr JHP...bulk price (500+ rounds) is $0.44 each so 2,350 rounds would be $1,031.
$1,031 to use all WWB JHP for everything, $544 to test a couple hundred premium HST and use high quality Speer Lawman for the rest.
I'm sure the numbers change a little depending on what kind of deal you get, where you get it from, etc, but I don't see how anybody who shoots very much actually saves money by shooting more expensive ammo for practice/bulk quantities. Even if you wanted to test 500 of the HST through the gun out of the first 2000 total rounds, that's still significantly less expensive than shooting all WWB JHP.
And the more you shoot the greater the difference since you don't need to continue putting hundreds of the premium JHP through to test function.
Does that make sense?
ETA: Let's just make 2,000 rounds the total round count, with 200 of those the premium HST (or whatever). That would be $473...so to spend less money using all one round it would have to cost $236 per 1,000....or less. And that's to have an inferior round in the gun for what matters, self defense.
Seems to me practicing with FMJ and loading/carrying premium JHP is both less expensive and higher quality.
That is why, when I see something like this (bold)
I carry Winchester White Box JHP's in my .40 and .45, because it has proven reliable and accurate in my guns, and it is cheap enough that I can practice non-stop with what I carry. I trust what I am "combat-proficient enough" with for shot placement, over the latest state-of-the-art 300% expansion, penetrates-any-cover-but-stops-in-BG bullets they try to sell. That being said, I won two boxes of Hornady Critical Defense .45's in Springfield Armory's sweepstakes last year, and loaded two of my 1911 magazines with them for winter carry, just because they are designed not to clog the hollow point with thick layered clothing. But, I wouldn't have paid the extra money for them, myself. I feel confident that WWB will meet my needs, if I ever HAVE need (and I pray that I don't).
I wonder if the person has done the math, or if they only shoot a few hundred rounds through the gun, because shooting all JHP at the range is paying extra money (and yet the performance of your defense ammo is still inferior)