Don't waste your time and money. Been playing for 3 years and occasionally paid for upgrade etc but was still very very weak. I've seen other spend 1k $ per month but still there were many other out there super strong. In some countries they can buy credits cheaper than sold in-game. So they rule the game. After 3-4yrs you will understand you've lost money and time. 11k -12k per year you can hire a team to develop. Game for you. Good luck.