Can someone describe potential for me?

Please, someone describe this "potential" thing to me. I hear it makes weapons like 10x better than normal.

It adds 2 or 3 lines of stats/misc stuff to an item only when the item itself has the line "slots". Doesn't matter how many slots it has. If it has the slots line, it can be potentialed. If an item doesn't have potential, use potential/adv potential scroll on it.

When it has potential, you can buy cubes from the CS to change the potential. There are 3 grades of potential. Rare, epic, unique. There are also (currently) 3 tiers of potential. 1st job, 2nd job, 3rd job. (1-30, 31-70, 71+) There used to be a 4th tier which was for VIP weapons only, but that was reverted to 3rd tier in chaos. Using cubes can upgrade (not downgrade) the grade of the item. Unique items have the best lines, from 1.3x damage on bosses to 15% ignore PDR, to 9% of a stat.

So how do I get these potential scrolls? Are they expensive?

5 cubes = 1 potential, 10 cubes = 1 adv potential. They also drop from all mobs as well as things like ani's box. They're 7m and 15-18m, respectively.