materials quote calculator

I'm looking to rebuild a client website, which includes an online quote calculator for materials (several options for price per material type, plus multiple entry/calculation fields) - the current quote calc is at http://ift.tt/1DlFJJr

I think I've worked out the basic logic for setting up the new calc; I've been looking at EZFormCalculator (Wordpress plugin), but can't work out how to get started.

Can anyone help with the best plugin to use, plus how to get started (so I can at least get all fields running and calculating for a single material/price?

Many thanks Rob