Painting bikes in general is not cheap at all hehehe In a matter of fact im still learning My paint jobs still suck Darn car paint is so expensive from 20 bucks a pint to over 100 the pint but the difference is heaven to earth type...

Nah the hardener is not necesary u can just paint using the thinner, just have to leave the frame drying for 3 days before start touching it and sanding the imperfections. At least under my experience u can leave the hardener out, but thinner is mandatory or you will clog the gun right away