The last one released was Renektoy and Super Kennen.
To be honest, I don't like all these flashy skins. I would always buy the ones that didn't have all these different cosmetics, not because I couldn't afford them, but because I just don't like particles flying around my screen. Some examples of a cool 750 skin is Bard Bard, Cursed Revenant Nocturne, Black Scourge singed, and Warden Karma. They're simple, but have they're own unique character to them, without breaking the scale on cosmetics.
Why not bring lower quality skins back? I don't see why this would cause any trouble, and I'm also not hating on the skin team because I think they do an excellent job.