User blog comment:SsVivid/Monetary Reference Table/@comment-4536066-20130820055911/@comment-4536066-20130820184013

I've explained already that these numbers have almost nothing to do with prices you pay in-game, Aztar. The game economy in RS reflects game mechanics, skill training, and the fact that most members of the world community are ultimate legendary heroes with access to supplies in the depths of black-demon-infested underwater dungeons. As for in-game shops, they operate to ensure availability of items to players (or, they did that back before the grand exchange existed), and not on the actual realism of how accessible items are to your average Joe swordshop owner.

The way I'm approaching this, rune is the sort of thing someone would either have to save up for over the course of a lifetime. I can explain why a bar might be 75k, though. We've worked out that one refined adamant bar is 3k. I did some research and found that RS can spawn up to 615 clumps of adamantite ore in one hour, whereas it can only spawn up to 29 clumps of runite ore in one hour. Therefore, runite is a whopping 21 times more rare than adamant. I took that number, 21, and rounded it up to the nearest 5 (so, 25) to account for greater difficulties actually finding, reaching, mining, and refining the runite. Therefore, the price of one runite bar is 25 times the price of one adamant bar: 75k.