I used to hand paint vans and trucks in coach finish (Tekaloid). You could get it mixed to any colour (non-metallic) or choose from the range. You could not tell the difference between brush, roller or spray painted because the paint would self-level over a couple of minutes. You needed perfect conditions (warm, dry, dust and wind free) and it would finish like glass. I've done cars in large home garages. I couldn't do it now as I no longer have a steady enough hand and I also haven't seen the paints around for a while (oil based). Such a shame because the paint went on thicker and lasted well (it had to on trucks going up and down the motorway in all weathers). You could spray it with no thinners (heated) or add a little genuine turpentine for a better flow on hotter days.
Ahhhh! The good old days!
As said by others above, the cost is in the preparation and the paint. I've seen cars in and out the same day! (or even half a day!) Get some local recommendations before parting with your hard earned.
Edit:-
Just found some Tekaloid!