A quick skin question if anyone can answer.

I first started playing League around a year and a half ago, and by the time I got more into the game I was thinking of buying some skins for some of my favorite champions, Twisted Fate and Vladimir for example. The skins I had wanted to get, Underworld TF and Vandal Vladimir, seem to have been taken off some time ago so I guess I missed my chance to get them then. My question is this. Is there any way to get these skins still, and if not, is there a chance that these and some other older skins will come back at some point as some form of Vault Sales type deal? I do apologize in advance if this is in the wrong section, or if this has been asked before, but I was just curious.