I know it may be something you don't want to hear, but the "expensive" 6300 champs, rune pages and expensive runes are the only thing we're working towards. The price represents accomplishment, can't give it all away for a few nights playing.
But after we;ve all been playing a year or so, you should be sitting on stacks of IP snd a few sets of runes.
I bought 1 extra rune page, for a total of 4 which covers me, and on average 4 sets of each type of rune i run, so i have everything i need, without having to be a completionist. 50 champs, always float between 17-24k ip or so. I buy about every 3rd 6300 champ (any support or brawler for sure), and it doesn't make much of a dent on IP. I'm kind of on the fence about the new armpen/mpen combo marks.