I guess it all depends on what you want the final result to be.
Lets see...

... to do an automotive quality finish properly you need to clean and degrease to remove any manufacturing lube used in the drawing/forming process and/or finger prints. Then a sealer coat. Then primer. Then sanding and more primer. If you want a true automotive finish, repeat this step several times until all flaws are gone. Mask the under side. If you're using a two stage paint (base coat/clear coat) there maybe several steps/coats to get the color down. Any significant trouble spots need to be dealt with prior to clear coat. The clear coats. Then with some systems you need to cut and rub out the clear.
Times 2 for two fenders.
Shop rates of $70/hr, that's 10 hrs not including materials/consumables.
Doesn't sound unreasonable to me for a quality job.
Spray bomb? Sure, that's just a couple of bucks and a little lava soap to get the over spray off your finger tip, but it won't look anywhere close to the same in quality.
Or you could take a stab at doing a little better job with prep and sanding between coats. A little more money, a lot more effort, and maybe okay results (depending on what you want the outcome to be).
You pays your money and you takes your choice.