What if you only have supplies in your backpack? Will then a short rest cost you 40 pcs?
If SR costs 2 pcs per character in your party, a party of 4 would cost 8 pcs per short rest. So, as long as you have 8 pcs in your combined party inventory as you travel, you can SR once. You could have 100 pcs at camp, but you can't SR if you don't have at least 8 on you as you travel.
This adds value to a party carrying food on them at all times. You can decide before leaving for the day how much you plan to short rest keeping in mind you'll probably find more as you go.
In terms of packs that equal 40 pcs, either store them at camp because they weigh a ton, and only use for LR, or how hard would it be for Larian to make them partially expendable? They're worth 40 to start, but you can use only 8 of the 40 when SRing. Now the pack is 32 pcs and weighs less and is worth less gp.
For me, it literally doesn't solve anything.
Increasing the cost of rest will in no way make the player stop using it, and more "encourage" to search every chest they come across, even if they have not done so before.
The player can buy supplies from traders and even more than double the amount of required supplies will not change anything.
Not that you need gold for anything in this game, even at the beginning of the game.
Given the age-old law of rpg, you won't even get to the middle of the game and you'll have so much gold that you won't have anything to do with it. Honestly, there hasn't been a game where at some point (usually sooner than later) you don't have millions of gold.
You might as well spend it on food.
Your solution can only really make a difference at the beginning of the game.
Again. It's not meant to "stop using" any type of rest in particular. It's to provide value for each type. See? That's where I think we've been falling short in the past. We're trying to create a limit for something that shouldn't be limited instead of trying to create value for both types of rest.
Who cares if you can use either rest indefinitely? If you have 100 camp supplies and you use 60 for a single LR, you might rethink another LR so soon. Why? I could just spend 30 gp buying more camp supply packs from the vendor? Sure. But if you don't NEED to, why would you? You COULD keep going with several 8 camp supply SRs instead of popping 60 after every fight. So why spend gold unless you NEED to?
And THAT is the point. It's not locking you out or limiting you. It's just encouraging SR and discouraging using LR between every fight. It is making each valuable in their own right.