why not just thin the paint out and spray it instead of roll it? that would give a better finish and mean less wet sanding. btw, the proper automotive paint for a car is ~$150 and then you can get an hvlp gun at harbor freight for like $25. you can find air compressors on craigslist for cheap if you dont already have one. air/water separator is like $10. so for less then $300 if your willing to put in the elbow grease for proper prep work and can spray properly youll have a MUCH nicer paint job.