Why do forces cost a ton more?

Because the forces are in the outside while relaxes are the inside. Therefore, forces are more visible. At a replay and if you don't edit, you only gonna see the force.
Many persons prefers to buy forces rather than relaxes and that's why they cost more than laxes.

Forces cost more because that is the main colour everyone sees in game.
Your opponent will only be able to see your force colour when you play against them.

EDIT: ninja'd