It depends. Most seem to hover in the neighborhood of around $.01 – .02 per word; take someone like this guy, who I've thought about hiring: http://www.mikesirota.com/fees.htm . A typical novel will run about 85,000 words, so he'll probably charge about $1500. I think these guys: http://www.bookdocs.com/ charge similar prices. If you want to publish a 250,000-word epic fantasy novel, that's obviously going to cost more.

How about cover art?

About $500: http://www.extendedimagery.com/info.html . You can probably find people charging more money or less.

This is a topic of great interest to me because I'm probably going to take the plunge in the next six months, if not sooner.