Won't let me buy champs that I have enough IP for.

Happened to me. You have to close out, then log back in. :/ If it still doesn't let you, contact support. (I don't know how to contact, just look it up)

Happening to me as well. I have 6400IP but cannot purchase any champions because of "insufficient funds" or whatever the error says. [slayer-jinx-unamused]