Currently, the purchase of an upgrade has to be paid in full by a single character.
I think “ordering of an upgrade” UI should be changed to allow partial payments from multiple players. When the fee is paid in full, the upgrade queues up and begins when the workers have supply.
This would make getting upgrades done easier and actually help the economy grow. As it is, not everyone is willing to pay the prices for upgrades and lower populated/weaker worlds continue to suffer from being underdogs. This system forces poor people to remain poor. Their only fault is that they care about their world.
With this new system, when a group of 30 defenders successfully repell an assault, they all get a silver reward. They all then can go to the upgrade NPC and invest that 30 silver into whatever upgrades are needed.
This would also bring more stability to capture points because worlds that constantly pull feints or unorganized assaults run the risk of feeding the defenders the coin needed to upgrade the control points.
Overall, it gives everyone an affordable way to help their world without feeling contributing would otherwise put them in economic ruin.
Also, add a reward system for players that do contribute. Place a “coin value” on Badges of Honor. For every X contribution a player makes toward upgrades, they are awarded X Badges of Honor.