I would like to implement a surcharge on the first item only.

eg I would like to add a €5 artwork charge to the first item sold at €10, thereafter all items would be €10 only.

So first item total should be €15 (10+5)

Adding a second item should be €25 (10+10+5)

I cannot get the pricelists to have separate prices for the same item.
All discounts/extra costs are added to all or no items.

Many thanks