For non-US users.
That leaves only 190 and so countries, do you expect to get any real information with that many details you've rained upon us?
Non-US can mean China, Germany, Salvador or Afghanistan, I'm willing to bet that nobody will ever be able to provide you a solution that would be the cheaper for ll four of them.
Probably P2P is the cheapest of them all, but the only problem that I feel like plagues the P2P market is that a lot of people are not fair with how they sell and buy their price, they almost always go OP when they're selling and go total cheapskate when they're buying. One example is the USDT P2P market in the Philippines, the price for buying is criminally low, they cut around 14% or so when buying USDT.
You just managed to contradict yourself in the first line.
I don't understand why people say P2P is the cheapest, with the P2P markets the seller/buyer is treating this as a business, he's making money out of this and you're going to have to pay for that when you're dealing with them. Have you ever seen a seller on P2P giving you a better price than the spot orders?