Payment part security risk.

[JustMark1]

First i want to say your project is awesome bro! seriously one of the best!

There is one thing i found. There is an security risk in the payment part.
The total amount to pay needs to be calculated on the server side. The way it is now you can change the total price in your localStorage and manipulate the price you need to pay.

This is something that people need to change before they will use it for a real live ecommerce shop.

maybe you can make a tutorial how to do this?
thanks!