[Perfectlap]

SeaNile31,
take my advice the only number that matters is your budget. Once you've got that set up evaluate each asking price just like a house.

"What has been replaced on this one that's still old and worn on the others?"?

Has car B with an asking of $13K already had the suspension overhauled if mileage is on the north side of 65K miles?
That can run $4-5K on parts alone. What about the clutch? With these cars you want to replace a few other things when that job is done which can bring the price to $3K. Then you have the common repairs for these cars like the AOS, waterpump/coolant tank, fuel pump. Those will set you back a few grand at independent shop rates. What condition are the tires in, especially the rears? You don't want to cut corners on tires and a new set of top shelf tires can easily run $1,200 with your mounting and balancing. A brake job with new rotors is another grand at typical shop rates.

Point being you have to evaluate how much life is left in all those original parts still on the car.
If the car was driven in extreme heat or cold, the longevity of these is greatly reduced. Put it this way, I drive my car year round but only on weekends. It's mostly been garage kept.
Yet by the time my car hit 70K miles I had to replace just about everything. I easily spent what the car was worth by the time everything was done which I staggered over a couple of years.
What you should keep in mind is that the asking price of the car means almost nothing until that car is inspected and you factor in the cost of common repairs. Many inexperienced buyers simply pay the asking and haggle down based on the outside appearance and mileage. Huge mistake. The first question should be "what has been replaced on this car". If the seller replies "it's not really needed anything" and the car has 70K miles or more, be very skeptical.