[Plugin: WP e-Commerce] Variable Length Products

I am setting up a shop that will use varible length products

for example cabels.
sold from 100cm – 1000cm
that makes a heck of a lot of variations on 1 product
What is the best way to set up something like that.
I dont want to set 900 prices manuelly for 1 cabel.

I would aprciate any help on this!

http://wordpress.org/extend/plugins/wp-e-commerce/