I've been saving up for Kled 
for weeks and now that I have the IP to buy him, I get a message over the unlock that says "not yet implemented". It does not say this for the champions below 6300, but it does say this for all of the champions that are 6300. Why can't I buy this dinosaur riding redneck psychopath? Thanks in advance for any information.
LostFr0st1 votesYou can buy him through the shop. The profile buying isn't in the new client yet.
Mandalorian 1171 votesOk 
. thanks
Mandalorian 1171 votesSo what is profile buying?
LostFr0st1 votesIt's when you try to buy a champ through the collection tab of the profile.^^ In the old client people were used to going to their profile to buy a champ rather than the store; it's not enabled in the new client yet though.
Rákãñ1 votesProfile buying is that you go into your profiles to see what champs mastery you have and what not. and buy them from there instead going from the shop.
Regardless of that, I had your same problem 3 days ago. I exited out league and opened up the Legacy client and was able to purchase the champion I wanted to with no problem.
Mandalorian 1171 votesI try to open the legacy client, but it just exits out and does nothing. Is there more too it than clicking on the launch legacy tab when you start up?
Rákãñ1 votesIt should closes out then starts an update/download to launch the legacy client and once it finished, you get the old launch pages.
You could right-click your league icon and open file location. and launch the one with the old icon too btw. At least I have the option to as it is sitting there to launch.
Mandalorian 1171 votesThanks