Depends on age of car as to the price, for a car less than 7 years old, The AA is £99 or £199, The £99 is more than enough and includes a HPI check. Yes they do list every fault but as long as you sensible and remember you are buying a second hand car that aint gonna be perfect then you gonna be fine. If you spending a couple of grand its a small price to pay for peace of mind and someone else checking it over for stuff that you may miss!!