Custom Picture Mount Price Calculator

Hi I'm a picture framer in the UK. I have a website that I would like to include a custom picture mount price calculator that customers can check the price and if they wish order online. I have someone who looks after my website and informs me he only requires the coding. The customer would enter the height and width of an opening, the top both sides and bottom width of border required, this would then calculate the outside dimension of the mat and the cost and show this by the mount. It would also need to calculate the cost of a double mount if required and a backing board if required. I also need to be able to access the programe to change the board cost if prices change. This link would best shows what I'm after and how it works works. I DONT NEED ALL THEY LIST. [login to view URL] then click on mounts, then click single opening mounts. I only need: Items... SIZES - STYLE - single or double mount - Mount colour/s - Options - is a backing board required and amount of bottom mount to show on a double mount, the customer to enter this dimension. Other things I can think of are a "clear" button if you make a mistake or want to start again, and an option to change colours again I require access for this, in case they discontinue any. I hope this makes sence. Regards KDA