The guys here don't lie. They also don't mess around, You can't when your doing bodywork. Don't expect a pro to trust a $10 gun on a $10k paintjob.
I use the infamous HF Purple gun to spray epoxy, but thats it. I get about 1 gal out of one before its junk, leaking past the seals, etc. I have a Matco tools gun with a larger tip for 2k primer, and a good gun for spraying color and clear. I don't have a dedicated base coat gun (yet). All in all, I still have $500
wrapped up in spray guns, thats less than some guys spend on a gun just to spray clear. You have to have a dedicated set up to spray. I use a inexpensive water separator regulator with a dessicant snake, and a dedicated air hose. SPI is fantastic epoxy, buy not if your gonna spray it out of a squirt gun with oily watery lines. I spent enough on tools, equipment, and materials when I sprayed my car, to have paid a pro to do it. In the end, I learned more than I assumed I already knew, and I have a car that looks like a pro did it.