Its a load of crap mate, the guy tryed to blag me. I told him my dads a painter and he soon stopped talking s**te.
No matter what paints been used it needs to be lightly sand'ed down unless it has big digs and pitts in which case it may need a bit of stopper. Then primer, paint and laquer.
Whats the finish like? If its just come off another car thats a different colour it will just need a light keying with some scotchbrite, and maybe some primer.
If you want You can get primer from halfords in a tin. Trick is to put the tin in some boiling hot water before you spray to get the pressure up, then a few light coats. Dont go to mad, else you'l get runs. Then see how much he'l charge???