You could also get an outsourcing manager to do all your work for you. for more helpful information on outsourcing and the like you can also visit www.thejonjones.com good stuff here, and if you have questions he will be happy to answer them (i'm sure).
I've worked for a lot of outsourcing companies. I would say approach some outsourcing companies and ask for a quote. If your budget is limited, individuals will cut out the middlemen and overheads, but it will increase the amount of management you guys need to supply as far as keeping consistency through the assets…
The paid job postings sub forum here would be a good shot, there are plenty of artists here who are into the art style you specified, so this is a great place to try to find some help. Be clear with what you're willing to pay, no one worth their salt is going to do art without worthwhile compensation, this goes for any…