How Influcence at Megacryptopolis could be calculated

I would like to share my thoughts about the Influence at MCP with you.
What would be fair to distribute the Influence ? For me its the payments a user did. So how could it work ?

Sure is.. no Building → no Influence. So.. lets have a view to the payments. Building a normal house at LvL 1 will cost 0,01... Commercial 0,0125, Mine 0,015... 3 different prices thats means if 3 people build a house, a office and a mine they get different influence. Overall they paid 0,0375. Houseowner gets 26.6% influence because he paid fewest, Commercial gets 33,3% and the Miner gets 40% influence because he paid most.
Now the houseowner builds an office (Commercial) at LvL 1 for 0,0125. The pot know is 0,05 Eth (0,0375 + 0,0125) and the influence is calculated new.

The Houseowner now has paid 0,01 + 0,0125 = 0,0225. Thats now 45% influence. The influence from the 2 other now drops to 30% for the Miner and 25% for the Commercial. BUT because a Commercial has positiv influence for houses the houseowner gets an extra 5% bonus becauce he build a litlle string. House → Commercial. At the end the houseowner now has 47,25% influence, the Commercial 24,25% and the Miner 28,5%.

In my opinion this could be the way how influence is calculated. Its a very simple example.. but as i think a good way to calculate influence

What do you think ?