Change tier 1,2,3 rune to a single rune system that lvls up as u use them more.
its simple make it lvlup along with the games played with that rune. This way u can make them cheaper and also ensure it to still have an impact later on. The only thing i have no idea is this will work very well from lvl 10-30+ but for lvl 30 players who buys new rune will have to go through the tedious task of lvling them up. So just make sure to make it no boring to lvl them up :D
I would dig this runes anytime over the current system cause man the current ones are not worth the ip when i have over 60 more champs left to unlock :'(
Gameplay side: This is a very good system too as players can understand which of these runes are also worth for that particular rune page combo u were looking for. We as a player get to play test our each build over many games and hence can come up with good combination of rune page that fits our needs.
Either like this idea, or like this one : single rune system that lvls up in game as well which is pretty much too op and ensures pay to win model :P