My client has decided to add oversized posters to their online offerings and it has wrecked shipping. They won't fit into a price based table because although they are one of the least expensive items on the site to purchase they are the most expensive to ship.

We thought of developing a weight based shipping chart and inflating the weight of these posters, but then it charges that extra amount for EACH poster...it doesn't actually cost much more to mail 3 posters than it does to mail one, but the system would charge three times as much.

Is there a way to add a surcharge to items that appear in a certain category? I could set up an oversized items category and all those items would have an additional shipping cost?

Does anyone have a suggestion on how to handle this? I am at a loss, and the customer is losing money on each poster sale.