I am creating a project/order tracker for a Solar/HVAC installation company. Materials costs have been changing multiple times per year, So I need a layman to update the price 6-7 times per year. 

My question is, what is the best way to accomplish this?

I currently have a subform that is inserted into my order form. When a product is selected, I want the price to be automatically associated with said product. 

What is the best way to reference the price and then change for price when needed?