Price Based on Size

[sds91]

Although I have experience making simple sites in HTML, and using joomla, I lack a whole lot of PHP knowledge and need some assistance achieving my goal here.

I will be selling art at variable sizes to the customers needs. I need a text input box that would allow them to input the width and height, changing the price accordingly so that they could order for their exact needed size. Prior though I don't want a price to be visible, because it all depends on their input.

Is there a simple way of achieving this? Or is there somewhere I could get assistance in getting that up and running?

Any help is greatly appreciated.

I'm running VM 2.0.18a, Joomla 2.5.6, and PHP 5.3.2