I am at level 132 right now, and have been camping for months. My income is close to 2 mil/hr. I have bought all of the best buildings that are available for my level. That's why I am only doing upgrades right now and no building is in construction at the moment.
It's getting a bit lame because of the fact that I have to level up to 135 and 185 for my next buildings, and there is no building that I can save money for. Isn't it an idea to make a 1billion dollar building? Or one for 300 million? Just to keep the players with a high economy hungry..