I bought my dart for 2000.00 and put wheels and tires /seat cover/carpet and a
shade tree engine rebuild (pressure wash and repaint) and drove it for 11 years and sold it for 5500.00 71 dart /6 at/ps/pdb
This is not really a valid comparison. Your investment increased in value over 11 years as the rarity and popularity of the vehicle changed. This is not a guarantee and is the exception rather than the rule. Did you factor in the maintenance, storage, and repair costs for the whole 11 years? Cost of fuel? etc.?
As far as the OP, you're paying too much for a common car to EVER flip it for $. You're buying common cars, stuff we see nearly everyday. It's never going to be worth anything if everybody has one. The bellybutton analogy. Either buy rare, or make it rare, and your value will go up.
(Make it rare? What? Ever heard of the stamp collector who bought all ten known examples of a certain stamp, and burned 9 of them publicly before selling the tenth?)