Most people underestimate the cost of 99 mage and 99 range.

Presuming that you Burst/Chin your way to 99, here an effective tip on calculating how much it will cost. Find out your average XP per attack, Example: Chins - 450xp Bursting - 400xp

Now, Divide the amount of XP you have to gain to 99 by the Xp per attack

Example: 7m Xp from 90 - 99 Range: 7000000/450 = 15556. The resulting number is the amount (roughly) of chins you'll need to get to 99.

Then simply multiply the amount of chins by the price of 1 = Cost of chins. Adding in the potion cost is very simple.

You do the exact same with Bursting/Barraging but remember to multiply how many casts by the amount of each rune for example; 8400 Bursts to 99 magic. 8400 * 2 = 16800 Death runes required, so on so forth.

Hope this helps. Make sure you get it before the combat rework as xp rate will be insanly nerfed.