How do I make a skill cost gold?

How do I make a skill cost gold?

How do I make a skill cost gold? I need to make a runner in my kodo tag game have that ability cost him money.

Thanks

Just use triggers to take away gold from the user who purchases the ability
The gold icon beside the name of the ability won't be shown though Like Nature's Call - Circle defense, the special towers

Thats what I thought but I wanted to show :/.

Here a trigger (Add property -> use negative values)

Events
Unit - A unit Begins casting an ability
Conditions
(Ability being cast) Equal to [Your Ability]
Actions
Player - Add -20 to (Owner of (Casting unit)) Current gold

Remember the icon for gold price won't be shown, so write " costs xxxxx gold " below the ability

btw I would use Color Template (on this site) to make the gold costs in color, like

costs 300 gold

So it looks more like the item- or unit-costs (looks better)

Well, the action should be;
"If (((Owner of (Casting unit)) Current gold) Greater than or equal to <ability cost>) then do (Player - Add -<ability cost> to (Owner of (Casting unit)) Current gold) else do (Unit - Order (Casting unit) to Stop)"

Öhm, yeah, right

Wonder if it would give the player a negative gold value, crash wc3 or simply do nothing if he casts having no gold.

use a floating text and color it