I need a custom AJAX calculator that will add to or subtract from 1 of 4 set fixed price points.
For example, say I want to make the price $30 over fixed price 2, I select "over" and "fixed price 2". The calculated value with be displayed in the input box "newprice".
This function will be used dozens of times on the same page so please make everything as generic as possible.
An example can be seen in the screenshot.