Crate Surcharge Extension

I am looking for a way to automatically add a crate surcharge to the check out.

I’ve looked at the Force Sells, Chained Products, and Bundled Products extensions, but they won’t work as needed.

I want the crate surcharge to be added once IF the particular product selected requires it, but limited to only a few products. Also, I want the crate surcharge to be added once, regardless of the quantity of the product’s quantity.

Any suggestions would be greatly appreciated.

http://wordpress.org/extend/plugins/woocommerce/