champion mastery is way harder to get now

its so expensive now. I have all champs(except zoe cause shes expensive too) so i remember being able to buy tokens on tokens as long as i worked towards it. now im playing tons of games and I leveled up twice, and i still cant mastery up 1 god damn champ. i have like 7 champs in my loot waiting to be leveled up. why is it so expensive?