There are commission painters on this site. If you check through the gallery often under their pictures people will say that they accept commissions. There are a lot of talented painters here, although many of them focus more on display level (10 out of 10 detail) and less on table top quality. There are quite a few studios out there that specialize in painting large numbers of figures, that may be the best option for you.
Ideally you should find a studio located near you (ie same continent), so shipping doesn't become a massive issue. Some internet searching for miniatures and painting studios should turn up some options. Of course you want to be sure to see examples of their work and check out reviews from other customers before you decide. One that I've heard a lot of good things about it Golem Painting Studio. It's in the UK, so that may or may not be convenient for you. But, either way, I recommend taking a look at their website. They do a really nice job of breaking down the different levels of quality and the associated prices. So even if you don't use them, at least you'll have a better idea of what to expect this sort of job to cost and what you should get for your money.
http://www.golempaintingstudio.co.uk/index.htm
You can also check around at your local gaming store. There may be someone local who does this sort of work.
Hope that helps!