A common query is how to achieve location-based postage.

This can be done very effectively through Product Options. There is the ability to add a product option that must be chosen (i.e. no "no thanks" option). So at purchase-time, the user selects their location and continues to have the product cost ammended accordingly.

http://www.freewebstore.org/support/controlPanel.html#addoptions details how to add product options

We have to let the user specify the delivery location, as although it is possible to detect the country a user is in, this would require the user setting each potential country with an associated cost. Also, delivery addresses are not always the same as the browser's address - so we will have to ask for the location anyhow, to make sure.