To give you an idea of price , a few years ago I heard of someone in Sydney charging $400.
Why not have a go yourself ?
Lots of work, $400 sounds pretty cheap.
Bunnings spray can job ? 
Nothing wrong with using spray cans IF you buy decent quality paint.
and some of them really are total SHIT! I always get the best results from Dulux brand.
For a couple of games i did in the past i had the colours custom mixed by an automotive paint shop, one of the games was a Silverball Mania that i got the blue custom mixed and put into spraycans, it was done for a mate of mine and he paid me $500 to do it (he offered that much i didnt ask for it)
Another mate who worked at the paint shop at the time did the colour matching AND got me the paint real cheap! I usually use enamel paint on cabs, but im thinking i might start using acrylic to save time since it dries faster, and using a spraygun/compressor setup, also as a time saving measure
As part of the job i also did some board work that was needed and reassembled and tested the game before he took it.
It was easily THE best cab repaint i've ever done, better than some of my own games
I've got pics of the silverball cab/backbox somewhere, if i can find them i'll post them
