My understanding of buying charms is that the game generates 4 lists and sticks to them. Every time you buy a charm it advances all lists. Reloading doesn't change the lists, so if you try every combination of gold and silver coins and you don't get what you want then all you can do is keep getting coins and trying again.
It's annoying, because it could take 8 playthroughs to ge the Striker charm but you could well be finished with the game by then. Because of the fixed nature of the lists, getting charms and duplicates doesn't nudge you towards new ones at all.
Thinking about the game as a whole, as much as I like the game I don't think it's as replayable as OG. The move away from arcadey into modern things takes away from it. Less fun weapons, more scripted moments, more taking away base function in favour of
game design
, as some would put it. OG gives you some guns and lets you run off, only taking away standard control for Del Lago and Ashley. No slow walks, no semi-in-game calls, no nothing. Just Leon, a worse Ashley, a better Merchant, and a better Krauser.