Literally, at what cost? That's the question a lot of players have been asking when the third set of outfits was released for the base roster of Street Fighter 6.
Many guesses that I've seen ranged in fairly ridiculous ranges, with some people going as far as guessing that they would be around 20 to 30 dollars each. While likely meant as a joke, given the wildly expensive TMNT collab outfits for your avatar, massive prices wouldn't be too big of a shock.
You can relax, though, but don't get too comfortable. While individual cost of them roughly comes to 5-6 dollars (as they cost 300 coins), buying all 18 outfits will take a measly sum of $100.
Since you can't buy these skins directly, you are forced to buy into the in-game "fighter coin" currency. The smallest pack of those is 250 for $7, and the next one is 610 for $12, meaning you will have either not enough, or too much if you plan to buy only one or two.
As these schemes often give you extra currency for buying more expensive tiers, the "cheapest" way to get all 18 costumes is to buy the biggest coin pack, which is 2750 coins for $50. At least you get all the colors with your purchase, so it could've been even worse.
Some might say that this is simply the current state of video games, and prices like that should be expected, but something about buying 18 skins for 100 USD in a fighting game that costs 60 USD just doesn't sound right.