How to create a BOM for use in purchasing

Hello Experts

We are a University, and I have been asked to create something similar to a bill of material for using on a purchase order.

We purchase light bulbs from a supplier, but each bulb also incurs a 15p disposal charge and this charge has to be shown as a separate line item on the purchase order. So we want to create a material that when used pulls through an additional line for the disposal charge. Also the light bulbs are held in stock and are issued out to departments, therefore the cost of the light bulb and disposal charge must be charged out too.

Thanks