e-commerce plugin for printing website

Hello Everyone!
I’m facing a minor dilemma with our wp project.
I work at a postcard and direct mail fulfillment company. We love the basic platform that wp offers and are considering adding online ordering to our site. However when it comes to choosing an e-commerce plugin we haven’t had much luck in finding a viable solution platform.
The problem is that unlike most shopping cart that handle t-shirts or dvd’s, printing services offer a wide range of pricing variables (qty,stock,tagging,turnaround,etc). In addition when you throw in shipping costs for various qty’s things tend to get out of whack.

So my question to you is: Does anyone know of a wp ecommerce plugin that can handle the complexities of printing website? Or does anyone have experience in creating a similar type website? If yes please pretty please letm e know how you went about creating it.

Any help is much appreciated!