Vehicle manufacturers are being accused of overcharging customers to duplicate or replace car keys that carry a computer chip.
Dog and Lemon Guide editor Clive Matthew-Wilson says locksmiths can provide copies of keys for older model cars for as little as $150.
But duplicates for most modern vehicles cost up to $700 and can be bought only from a dealer.
Mr Matthew-Wilson says the companies usually reprogramme a car's security system to match the codes on new keys, at a cost of about $4500.
Toyota says restricting the sale of duplicates to dealers keeps information about the security system out of the reach of thieves.
