What do you mean exctly?
The cost of a product is the exact price of something. In business if you bought some components of a product for a pound but you had to ship the product somewhere, insure the goods, employ staff to manage, this process this could cost an additional 50p. The cost of the product would now be �1.50. If you sold this on but wanted to make a margin of 100% the price would be �3. If a retailer also wanted to make a 100% margin the product would now be �6. This would be the price the consumer would pay. This price is the cost to you- although not actually the true cost of the product. Does that help?