Renting Champions
Here's a thought. Why not implement a renting System so players can try out champions. Say I want to try out Vi who normally costs 6300.
If you pay only a forth of the price (i.e 1575) you can rent her for a day or two. Plus if you decide to buy during the duration of the rent, you'd be discounted the price you already paid. (i.e while you are renting Vi, she would cost 4725, but once the rent is over she goes back to being 6300)
I know that free week champs allow us to try champs for free, but we don't have control of what champs become free. Why not give us this option?