Tips when buying a Ford P71?

I always wanted a Ford Crown Victoria Police Interceptors and I'm super eager to get one now because Ford stopped making them. I know they have a prone oil cooler seal leak and I'm pretty sure even if I do find a decent one, the ball joints and suspension/steering system will eventually need replacing. I do know that they are gas guzzlers and do use a lot of oil when doing an oil change. I'm looking at P71s from the year 2003-2011.
How much should I pay for one and for which specific year?
What should I look for when I'm buying one? When should I walk away from a deal because the P71 will conk out in like 2 years?
How can I know if someone is trying to cover up something bad, like they used Lucus Stop leak for almost every fluid there's?
Also, if I buy an 03 crown vic, is it possible to put in an 06+ dash? I like the tachometer.

The 2003s had a one-year only plastic tensioner on the timing chain that eventually self destructs. It needs to be refitted with a steel replacement. But your best bet is to look for a 2004 or newer model.

Also, are you sure you want the P71 model? The main advantage it has over the civilian version is a 3.55 limited slip diff in the rear axle. That was an option on civilian cars with the HPP package. The P71 is going to have a cheap interior with no carpet, bucket seats upholstered in tweed, the rear seat will be cheap vinyl, you might get an AM/FM radio, but there won't be anything else in the way of options, there will be a big gap between the seats where the armrest should go, the car is liable to have holes drilled in the dashboard and body work at weird places for police equipment that was removed prior to the car being sold, and they call them "Vomit Comets" for a reason. All the drunks and druggies that got arrested and tossed their cookies or soiled themselves in the back seat.

Buy a civilian Crown Vic or Grand Marquis. Much nicer interiors, and if you get one with the HPP package, you'll get the lower 3.55 gears as well.

Or find a 2003 or 2004 Marauder. It's as nice as a Lincoln on the inside, has a performance oriented suspension, and a DOHC 32V V8 engine good for 50 more horsepower than the P71

Here in AZ some auctions take credit cards the state surplus is one… You can talk to your Credit Union, or bank get preapproved. So you can just run to the bank andreturn with payment… Some you can have two business days to return with payment, they usually require 500 cash to get a bidders number… Don't know of any Police agency that holds their units together with magic juice.Could only image that being on a service record after an accident… But it usually takes a big repair to send to auction few go just on age… Buy one with the tach… Prices at auctions are crazy many times local cab companies compete. Most have no back seats, door panels, locks, controls etc. Look for one that has them it probably was used for other then enforcement and had an easy life.
No used car is trouble free for two years, I normally would budget 2000, for repairs. Plus body and interior. The day you buy it… Roll that in your loan if your going that way… Prices vary go for 1/2 of book or less

Go with rick