Is it possible to make restrictions by all orders total value. For example one user could make orders not more than on 1000$. So if he first time have bought something with price 600$. And if he come on site next time an going to buy something with price 500$ for example he should not be able to make purchase because 600+500=1100$ which is more than 1000$. In other words when user doing purchase, system should check how much he already spent on site, then add to this value price from the current car and check if it not more than limit that we need.