I just bought some more champions today, I'd post a picture but I'm not sure how.
I bought Renekton and Thresh, so now I have:
Alistar, Annie, Ashe, Caitlyn Corki, Garen, Graves, Jarvan IV, Kayle, Lux, Master Yi, Nasus, Nocturne, Nunu, Ryze, Shen, Sivir, Sona, Soraka, Taric, Tristana, Tryndamere, Twisted Fate, Udyr, Vladimir, and Warwick.
It is surprising just how expensive this game can be, I've now spent $65 on it and I'm not even level 30 yet.