would recommend going there in person if i was you, always seem to get better prices if your there in person and its easier to haggle with them then. make sure you get a price before you get them off the car, once you have taken them off the car they can be pretty sure your not going to walk off for the sake of £20.
would aim to pay maybe £30 at the most if i was you, whatever they quote you can haggle anyway and there money is made in the metal, anything else is a bonus so dont let them rip you off!
sorry if that all sounds a bit obvious, just things iv picked up on going around scrappys for the past few years, tbh they actually seem quite happy to haggle around here!