Why are jewellery valuations so expensive?

Took several pieces of jewellery to a shop to be valued and they want £37 for the first piece and £15 for all others. when i questioned the price i was asked is it for insurance purposes? is this a bit of a rip off do you think? should i be going to a high street store instead such as samuels? if i wanted to sell the pieces would it be cheaper?
Answer
Most evaluations charge a percentage of the value of the item