Here's whats left of my collection of old school siphon feed guns. The good ones were stolen (along with most of my good tools and boxes) when my truck/enclosed trailer were stolen while moving to FL. None of these have been used in a couple years. I should just sell or give to a young guy. I even still have a back up gun brand new in box.
Here's the currently most used group of HVLP guns in pic below.
Left top, my go to high build primer gun a $12.00 Harbor Freight 1.5 tip with a 20 oz. cup. The smaller cup size makes it easier to get under things, isn't as tippy as a big cup, and is lighter. You can lay primer just as smooth as you can with a high dollar gun.
Next to the primer gun is a Harbor Freight 1.4 tip with 20 oz. cup. Mostly a back up gun for paints but sometimes I use it because of the smaller cup, lighter weight than a full size aluminum cup gun and sometimes I use it for thinner primers like the epoxy primers.
Vaper full size aluminum cup with 1.4 tip gets used for panels and parts single stage enamels and urethanes. Never used it for whole car or other big jobs and consider it a back up gun for big jobs.
Right top, Vaper 1.7 tip with full size aluminum cup rarely used, just for laying thick paints or undercoats etc.
Lower left, The 2 small jamb guns are both 1.0 tip guns Vaper on the right and some other house brand on the left. I use them for small parts and small spaces only for paint, not primer.
Devilbis Techna pro lite in pic below
http://www.autorefinishdevilbiss.com/products/tekna/tekna-prolite-premium-spray-gun.aspx gets used for overall final primer/sealers and/or paint occasionally. Comes with multiple tips.
Not Pictured, SATAjet 3000 gun that gets used for base/clear large jobs. It's at the body shop tonight but I'll get a pic of it and put it up. It's the go to gun for all top coats on higher end work and big jobs. The adjustments and ease of use are nicer than less expensive guns (smoother operation) The fan adjustment and pressure adjustments are more concise and accurate. Atomization is better and when shooting clear at higher pressures allows you to lay a nice smooth finish that doesn't require buffing. It's a pleasure to use.
You'd be surprised how nice a finish you can lay down with a cheap Harbor Freight gun. I'm amazed at what you can do with a gun you only pay 10-12 bucks for on sale. They don't have the smooth trigger action and "feel" of a higher quality gun and the adjustments aren't as nice but with a bit of practice you can certainly put down a nice finish that doesn't require sanding/buffing. Those hinges in my post above were shot with a HF gun and were dry to the touch when pic was taken. I put parts like that out in sun for a couple days to really harden up the enamel. The roll cage base coat and matte clear were shot with the HF gun with 1.4 tip also.
Best tip I have is to have a back up for everything. I have a backup compressor, lines, filters, regulators, guns, 220 outlet, inline filters, water separators, face mask. And I make sure I have extra of all consumables, thinners, strainers, cups, rags etc. This way there's no worry if something should go wrong that you'll loose the window of opportunity before paint hardens in a cup or base dries before clear is ready if something goes wrong with equipment.