One extra arm costs 10 points, two extra arms costs 20, three costs 25, four costs 30, and five or more costs 35 points.
When grappling, if you have at least 50% more regular length arms than your opponent, you get a +1 to maintain a grapple, pin, break free, resist a pin, takedown, choke, strangle, constrict, choke hold, arm lock, neck snap, or wrench limb. This bonus increases to +2 if you have double or more the number of regular length armos of your opponent.