Everyone is asking why the earlier buildings (like Newspaper Stand) end up costing more than the later buildings (like Oil Rig).
So here it is. Every time you buy an upgrade to lemonade stand, the cost of the next lemonade stand rises 7%. Every time you buy an upgrade to newspapers, the cost of the next rises 15%; 14% for car wash, 13% for pizza, and so forth down to 7% for Oil Rig.
So if you've bought 300 Newspaper Stands, the cost is (1.15^300) = about 2 quintillion times the starting cost (about $100 quintillion). But if you've bought 300 oil rigs, the cost of the next is (1.07^300) = about 600 million times the starting cost of one oil rig.
It's not a bug. It's exponential growth in action. The higher your upgrades, the further ahead you should be with oil rigs and the further behind with newspaper stands.
 "AdVenture Capitalist"){kind=icon}