Some of them have versions with different colors in the other regions.
So you have a decent chance of seeing them with different color and a different name.
Just not the exact same as founders.
I don’t recall what they all look like, but for looks maybe the Shadow Hunter skin because it has demonic wings.
If you mean unique as in rare due to low class representation, then maybe Deadeye? I say that without any source to back it up, besides reading that Deadeye is a hard class to play so less players would claim the skin on it I assume.
Possible yes, but they are probably paying a large price tag. To get all 15 (I think?) skins they would need a bit of gold and pheon coins. The skins were cheaper last week after launch, they’ve over doubled from when I last checked. But with second founder chests going out they may drop in price for a few days if the market gets flooded.