I played LoL months ago and began saving IP. I intended (and still do) to buy runes upon hitting level 20, using just free heroes until that point. Recently I started playing again with a friend who was surprised to see that I have Corki "purchased" on my account, who is in the most expensive tier- actually costing more than I've earned total to this point. He's also quite easy to dominate games with, though he seems to have been nerfed substantially from when I used to play.
Was there once a way to unlock him, or was he just at one point substantially cheaper and I splurged without remembering so?