Every state can sell its resources on the State market.
Every player with level 60 or higher can make a donation to any budget, there is a special exchange rate when donating gold: 1:500000.
Travel fees, which can be set in case the borders are open also add to the budget.
Obtaining budget in war
In case of a success in a war against other region with a budget (capital of the state), the winner state takes all the money and resources.
Closed borders and residency issued by the leader
You need to spend money and resources to be able to keep your borders closed or residency issued by the leader: budget will be charged every minute, borders will become open (or residency will become free to get) if your budget is less than it needs to be.
Buildings are one of the most important part of the state and it is the most costly one.
State market allows you to buy resources you need.
You need to spend some resources from the budget to start a war. The more active wars your state have the more expensive next war will be.
Normal and Deep resources explorations also need some budget spendings.