In our salon- we charge extra for added bowls of color, we also charge for extensions by the number of extension pieces used. It would be amazing if you could select the service once in the checkout screen and then be able to select the number of items and it would charge accordingly. For example, we would add an additional bowl of color to the checkout screen, which we charge $15 for.. but say the stylist used 3 extra bowls. You could select quantity of 3 from a drop down and it would adjust the price to $45.