Sit back, and get ready for a lesson on why it is so expensive.
Your car is painted in metalic paint. Metallic paint, with alot of mica in it (The metallic part) is very unstable. If not used, it will cure in the can much faster than normal paint, and thus the batch will be ruined. It is pretty much use it all or none. That is why some metallic touch up paint does not exist (Like Ford type K7 metallic Royal Blue). It will congeal in the tube or can before you can use it.
First off, paint and accessories is expensive to begin with, because of the volatile stuff in it. You are paying hazmat fees, liability costs, pollution costs, etc.
Now, we get to automotive paint basics. Lets paint a whole quarter panel.
After ALL the labor of getting it to bare metal (Stripping, sanding, repairs, removal of trim, etc) First, you spray self etching primer, usually called Variprime. Then you spray your first color coat. The enamel is mixed with activator/reducer, gloss hardener, fish eye eliminator, then thinned with Xylene if still needed. After a few color coats and wet sanding, then you spray the clear coat (Which also has activator/reducer)
By the time you are done, here is an approx of costs....
1 gallon DuPont Centari acrylic automotive enamel, candy apple red, nonmetallic - $116
1 gallon activator reducer - $20.17
1 quart gloss hardener - $16.99
1 bottle FEE - $46.50
5 gal Xylene - $35.00
1 gal clear coat - $33.75
1 gal activator/reducer - $16.99
1 gal Variprime - $50
1 gal reducer -$23.00
Sandpaper - $20
Total cost - $378.40
$378.40 in supplies alone. Add labor, parts, consumables, etc and it gets expensive quick. Paint is not cheap in any means.