One time charge attribute for a category of products

Hello,

I'm selling documents that I ship on a CD. I have a category for these products and I need to charge the customer 10 euros for the CD and ~5 euros per document that I put on the CD. (Maybe in the future I will offer the docs as downloads or prints.)

I made an 'CD-fee' attribute but I got it to work only per product. How do you charge for the CD only one time for these types of products?

Is it possible to make an attribute that is charged only on time per order if a certain type of product is in the cart or can I make an 'invisible' CD-product that is mandatory for these types of products?

(I'm also selling other types of product so I (probably) can't put this cost of the cd as a shipping fee.)

Thanks.

Please help...I need this too! I'd like to have add an oversized shipping fee to any order that includes items from a certain category.

Without seeing the sight, I'm guessing but,1. set the CD price to 10 Euros
2. Have the options for the CD in radio buttons with the price for each as part of the attribute.When the customer orders a CD with three docs, the 25 Euro price would be there and the 20 Euro price for the customer that ordered a CD with two docs.

Make sure the customer has to select something by using "Please Select ..." as the first attribute and make it default -- for display only.