How was BE calculated from what I had? Money i spent got me very little.

Had 20 rune pages. Most of the level 3 runes some UP and just got 29,000 BE. Which doesent really give me much. I cant even get the URF skin I have all the champs but 3 that I don't really want. What gives. How was this calculated? I must have paid hundreds in runes and pages over the last two years and just get 29000 BE in exchange?