{plugin:ecomerce?]Free ecommerce plugin recommendation.

I’m just not sure on the best/easiest /time expedient way of accomplishing this. I’m hoping there is a plugin to help.

I’m setting up a wordpress site to sell my photographic imagery. Each print will have three or four sizes, which I hope to display by way of a options dropdown on the product page. Now how do I deal with shipping?

Item A has three sizes: A-1, A-2, A-3, the sizes are(examples):

product number:A-1, cost: $2.00, 2x4inches – 8square inches Shipping cost: $1.00
product number:A-2, cost: $4.00 2x6inches – 12square inches Shipping cost: $2.50
product number:A-3, cost: $6.00 4x8inches – 16 square inches Shipping cost: $4.00

Because it is the same print, I want to show the image once on one page. I would prefer to have a zoned shipping cost, along with a lower shipping price for each additional print ordered. I want it fair to customers as well as myself. I live in Canda.

With everyone’s experience running a ecommerce site, shipping, coding, etc, what is the best way to go about this? Is there a way a plugin to accomplish this? Is there a plugin with workarounds to accomplish this? What way is the most honest way to accomplish this, not over inflating the shipping cost, not raising the product cost too much, and not short changing myself.

Thoughts, insights, explanations, clarifications, thoughts and answers are deeply appreciated and welcome.

PChuprina