Using the MarketPress eCommerce Plugin for Fabric Store

I am developing a website for a lady who wants an online fabric & quilt store. A lot of her products are straight forward, using one price point. I want to offer a place where a customer can type in a certain length of fabric and it will know the price. For example. She sells 1/4 yard, 1/2 yard, 3/4 yard and 1 yard increments. So someone may come along and want 1/4 yard and type in .25 and the price would simply take the 1 yard price and divide by 4. Make sense? Is there a way to provide this feature for my client using this plugin? Thanks