What allowed the colonies to become more financially independent from great britain?

A diverse economy, representative government, and few restrictions on trade. 

The colonies had trade, shipbuilding, cash crops, and food farming.
They also had the advantage of representative governments who were allowed to make decisions for the colonies. This included creating currency and trade agreements.
Lastly, Great Britain had few rules on trade until the Navigation Acts were passed and the end of salutary neglect. The colonies were able to create trade agreements with the French and the Dutch in addition to the obligated trading with Great Britain.