I would like to purchase a new paint gun and wanted to know what is the differenc between a $150.00 gun and a $400.00 gun.  Do I really have to spend a lot to get a decent paint job?  

Well...
It's a system - the better the equipment, the better chance you have of getting a good result.  That said, I shot my car, another car and various parts with a siphon gun I bought at Walmart for about $40.  I upgraded later to an HVLP gun that was recommended by the knowledgeable guy where I buy my paint - that one was $99 and it's working really well.  I bought a spare for use with just primer from Harbor Freight on sale for $20.  Works fine.   Check with Eastwood - they have sets of decent guns (two or three guns in group) for under $200.  If you are expecting a show quality job and/or expect to paint a lot of cars it would be best to buy as much gun as you can afford.  Or better - two, one for primer and one for finish.

The biggest problem a home painter will likely have is water control.  If the compressor can supply the air and the gun lays down a decent pattern without spatter, your big problem will be keeping water out of the air lines and ruining your work.

90% of a good paint job is the prep, not the paint.

If you have the patience to sand the multiple coats, you could paint a car with a roller and Rustoleum.  

I got this from the Eastwood Company's website:

  "The StartingLine by DeVilbiss Auto Painting and Priming System is a complete gun kit to spray all of your primers, colors, and clears. Includes two full size HVLP spray guns, one with a 1.3mm tip for all of your color and clear coats and another with a 1.8mm tip for primers and sprayable body fillers. Also includes a 1.5 tip, two 20oz. aluminum cups, air regulator, cleaning brushes and a wrench for easy disassembly. Requires 13cfm at 30 psi. Packaged in a blow molded case with handle. 1 yr. manufacture warranty. $125.99"




Dang good price for a quality product, if you ask me...
 

If I didn't already have a set of guns, I'd snatch those up.  Good stuff, good price.  Good post too - I forgot Eastwood carried those.  

Hey eddies66mustang, do you still have those set of devilbiss guns??