What company will you be shipping with?
Remember that FedEx and UPS typically have a minimum amount they charge and you could also run into other fees that you might not expect, like address change fees, and residential address fees. I would consult with the shipping company and make sure that you undersatand all their fees and see if they can provide assistance with the setup of your site.
I am noticing that more and more people are moving to free ground shipping and building the shipping in to the cost of the items. Amazon has changed the way we do business online.