I would do them yourself mate.... its good thing to learn and really isn't that hard, especially if they are a simple desing (ie not bbs!!!!)
Start by sorting out any big kerb marks round the edge of the rim - best with the tyre off. sand/file/ what ever you have to do to get it smooth!!!
Then sand the whole wheel with something like 120 grit.... if there are any chunks missing on the face of the wheel then use P38 body filler from halfords to fill - it is easy sand (apparently!!)
once you have sanded any repairs flat with the 120, go to a higher grade (poss 180/240) and give it all a good sand. At this point if the surface is still obv keyed from the higher grit paper (ie if you painted it you would see the scratch marks) then you need 2 types of primer - high 5 from halfords is a high build primer that will go on quite thick and go over any little marks....
sand this back with 240 or higher until totally smooth then use a normal silver primer.... you can sand this back once dry but if you have done a good job before hand you can just top coat over the top. I would do a couple of coats of primer followed by 2/3 coats of top coat and then maybe 3 coats of lacquer...
sounds a lot but remember a 'coat' takes roughly 30 seconds..... best to prep two wheels at a time and then paint at the same time to speed things up..... you will probably find you do 5 wheels, as by the time you have done four you will have learnt a lot and want to re-go over the first wheel!!!!
good luck, its quite rewarding - might do a how to guide when I do my next wheels
