Rentals are good for trying out equipment or for short projects requiring specialty equipment. If you are going to photograph one product at 4X magnification, during one week or less, and never expect to do so again, yes, rent a specialized macro lens. If you are considering buying one of 3 possible $8,000.00 to $12,000.00 super-telephoto lenses, and want to get a feel for what you can handle, rent! Better to find out that you can't handle the 12 pound lens comfortably before you buy the thing. If you are considering moving up to medium format, rent these expensive to very expensive cameras (and lenses). A week's rental with full shipping and insurance seems to be approximately 10% of the purchase price of the item.