4th rate ships should use a combined midgrade/high grade upgrade system to make them more economical for the players that will be using them.
My idea is to change their upgrade costs to such.
Basic 0
Common 1 Mid grade note
Fine 1 Mid 1 High
Mastercraft 2 Mid 1 High
Exceptional 2 Mid 2 High
thoughts? suggestions to make this better or relate to other classes of ships?