Seems like there are a million guys on various classic and rot-rod type forums who swear by the cheap Harbor Freight HVLP guns. I will allow that they do an amazing job considering how stupidly cheap they are and I do own a couple that I use for certain utility spraying tasks and don't own me a thing. Many good paint jobs have been accomplished with them I don't doubt. The problem with them in my mind the the lack of efficiency. Now, they will get more of the paint on the vehicle than the old cup gun style for sure, most of those rigs were only 55-60% transfer rate, the rest wound up in the air. The HF gun might be more like 75%? Still a lot of paint in the air. When the paint was cheap lacquer that was fine, but some of what I shoot is $600/gallon so blowing 25% of that into the air just hurts my feelings. Do a few paint jobs and even an expensive gun pays for itself. The other thing I don't love about the HF gun is it's an air hog. something like 17CFM. So, you need to take a lot of breaks if you have a little compressor which kills your flow if you are painting a whole car. My Anest gun is supposedly able to put 90+% of the paint on the car and do it using just over half the air of the HF gun. I happen to already have what most would consider a large compressor, but it's nice to have it not run all the time getting my air all wet, it's also really nice to not have the paint dust hanging in the shop.
Speaking of equipment, get thee to a popular online auction site and buy thee a PAPR! Seriously, a lot of the automotive paint WILL mess you up. You don't have to spend $1200 for a good setup, $50 for a used blower, $10 for a hose, 25 for a hood and $20-90 for a filter. A little know-how and some scrounging and you can have a good setup to spray in for as little as $200. If you bought a big compressor that's far from your spray area you can run supplied air instead of PAPR, but get something better than just a half-mask.
A decent middle ground on the gun front I think is the 3m Accuspray setup. If you shop hard you can get a starter kit for about $200. You get a gun with air caps from about .8mm to about 1.8mm and I love the fact I can shoot at weird angles with the PPS cup setup. Another up-side is cleanup is quick and easy. The down side is it's a mediocre gun that's going to cost you a lot in consumables. Great gun to learn with though if you are new to the gravity-fed HVLP realm and want to try out all the different paints and tip sizes. Plus you can epoxy, prime, base, and clear with just the one gun.
The other less-is-more approach is to get the lowest pressure gun you can, forget HVLP, LVLP is the new "it" gun.
Spend I think $300-600 and get something that gets most of your paint on the car and just sips air doing it. Hopefully spending the money on the gun means you can get by with a small compressor so saving money there.
Air dryer, you can DIY one with just a bunch of pipe. You can even use PVC pipe if you cool the air a bit first. I've also seen folks run the air line through a water tank to cool it to separate the water. Anyway, it's nice to have a dryer of some sort but DIY is fine and if you make one out of enough pipe it increases your effective tank size as well.
Me, I run a big compressor and just drain the water before I spray, then I have a chemical-type desiccant filter just before the regulator.
