Replace key locks?

[E.Mk]

Hey all,

I'm on still on the search for the ever elusive manual transmisson(hopefully), under 50K mileage, 2000+ year model Ford Convertible for under $10K when I had a thought.

I have never bought a used car(I have never bought a car, period), but I assume that if you were to buy a used car from a private seller(read: complete stranger), it would be in your best interest to have the car locks replaced?(You never know... paranoia of if I'm driving a used car and someone else might have a copy of the remote keyless entry or something).

How much does that go for nowadays and what companies do you all recommend?