Wordpress E-commerce Custom

I’m in need of a Wordpress developer that also has worked with WP E-Commerce plugin to look over some customisations I have done. It is a Printing Commerce website.

I’m struggling with custom field’s I have added to each product called design hours each product has an option before cart to select from:
- Upload artwork myself (Working)
- Make artwork print ready (Working)
- Design this for me (Not Working)

I need the following working:
I need the price to get carried over to the artwork page to calculate the cost of design hours if they select that option. Then to add the right product (Design Hours is made as a product) to the cart which are already created in WP - Ecommerce.

If you need more detail please don’t hesitate to ask questions.