What I did is when harbor frieght had thier 2 quart pot spary on sale for $20 I bought 5 of them. The tip was 1.9 which is a little small, but not really a big deal. It does take a lot more sanding. I was actaully amazed using a POS hf gun, lots of air pressure I got very little peel.( then again maybe my decade of sparying exp helped.)
Gel comes in basicly 4 forms.
ready mix color( very basic selection)
white
tint base
and clear.
The good thing about gel is its the same color wet as it is dry, so matching is easier if you know how to color match.