Here is one;
'99 Boxster needs engine
Go see the car in person with cash in-hand. Do a good PPI on the body, suspension, brakes, etc. Then remind the seller that there is likely to be a LOT more wrong with the car than just the engine itself and there is no way for you to check without the driving the car; e.g., a/c, alternator, starter, AOS, water pump/cooling system, suspension, alignment, transmission, etc. Nicely remind the seller that any of those items can cost $500-$1000 to fix and you're taking all of the risk in buying a non-running car. Therefore, you have to assume that there is more wrong with the car than just the engine. Then offer $2800. The owner will refuse that offer but now you can negotiate to low $3K's where the deal makes sense.