In short, the cost calculator above will generate prices of between £330 and £400 for a single radiator cover. If you order three, the unit cost will likely be close to the £330 mark.
The delivery costs are indicative only. The actual delivery cost to us is often as much as £90. When we charge £50, we are effectively subsidising the courier's charges because we are saved the trouble of fitting. Depending on your address (and if we can get two or more deliveries to the same area) we can sometimes reduce the price of delivery a bit.