On the bottom of the economy page, there's a breakdown of merchandise.
One of the categories is Arena sponsorships.
How does one get income for arena sponsorships ?
From the arena designer. You can choose between 200k, 500k, 1M, 2M and 4M. But be careful if you choose for example 500k and after that you want to increase to 2M, you will have to 2M, not 1.5M!
I have a 2M design and I regret to not have purchased a 4M one. Now it's too late :(
Joe
If I'm not mistaken, it gives a specific weekly amount. So in the long term, you're bound to make a profit.
I'll buy the 4M one if I can't avoid getting a fan boycott.