If you want it to be correct cheap really isn't an option unfortunately. The yellow you might be able to save a little on but the purple is House of Kolors Violet Pearl #PBC40. No other color will look like it should especially on an 1/8th scale where you are supposed to duplicate the real thing as closely as possible. The HOK is basecoat/clearcoat so you might as well do the yellow the same way, lay your graphics on then clearcoat. TCP Global sells smaller ready to spray bottles which will save you a significant amount of cash over buying a pint or quart of the PCB40. I have built all three years of the various Smokin' Joe's unlimited in 1/8th as well as SJ themed cat boats and monos. I still consider it one of the best paint schemes ever.