money, lots of money!
if you want a good job plan on spending money, it takes a LOT of time 
and remember, if someone else paints it you get no appearance points..

I am curious, why you want someone else to finish your plane for you?

After thinking about this, my answer may have sounded a bit smart alec,, for that I hope I didnt offend?
I also thought to look, your in Australia, so BOM and such dont apply like here.
I fear it may be a challange to get someone who knows about models to paint it for a reasonable price, there is a lot of labor in making a plane nice, and light both.
A motorcycle paint shop may do it, but again, lots of money, and they wouldnt understand about the need for lightness,,,

Many moons ago, (early '70's) a friend of mine used to be friendly with a local car repair garage. My friend would cover and dope the the model, then take it to the garage, who would prime and spray in any colour he wanted! He would trim it, then the garage would fuel proof it! A very reasonable finish was obtained!

Cheers   Neville