I am looking for the same actually - a payment checkout system for bitcoin on cs-cart.
Let me know maybe you can sell me a modified version of what you work on right now.
Quoting another job you recently accept:
I am looking to design a Bitcoin marketplace which obviously has to accept Bitcoin payments! The e-commerce solution I will be using is CS-Cart Multi-Vendor.
I would like for you to integrate Bitcoin payments into the Marketplace in a way that is functional and easy to use.