Free estimates and no call out charges – are they realistic?

When looking for someone to repair your appliances do you insist on using someone who offers free estimates and no call out charges? Do you think it outrageous if a repair company wants to charge you £40 (or even more) to send an engineer to diagnose a fault on your appliance? Did you know it can literally cost a company more than £40 in real costs just to send an engineer to your house?