I have to crunch prices in my head but I always base it on what I would pay for a BOX of ammo. So for the most part that's 50 rounds for pistol ammo and 20 for centerfire rifle.

I got rid of my last 45 in 2010 but IIRC back then, brass-cased, reloadable practice quality ammo was ~ $12 - $15/box (.24 - .30/round) with non-reloadable Blazer or steel-case ComBloc ammo for a buck or two less. If you shopped around you could maybe find some bulk reloads for $10 but that was hit and miss. Even during the post Sandy Hook ammo panic I think it was rarely over $20 for a box of practice ammo (i.e. SWC, FMJ or LRN, not hollow point or fancy 'defense ammo.') One of the main reasons I got rid of my .45 was the cost of feeding it (ditto for the .40 S&W) compared to 9mm, which is both plentiful and cheap, relatively speaking.

So to me, $.50/round (or as I would think of it, $25/box) seems a little high, but I wouldn't say excessive. I wouldn't pay it, but then again (a) I don't have a .45 and (2) I'm pretty stocked up on 9mm and .38/.357 anyway so I'm not in a panic buying mode. Others who might be could consider $25/box to be a reasonable price for a limited commodity.