Are you looking to hire for in house? if not, does the artist need to be located in Phoenix? I do work for many companies all over the globe without being on site, just simply using the internet (email, chat, skype, ect..) to discuss the projects and send the digital files.
It's ideal to have a graphic artist on site for faster turn around but contracting out the separations and or art work maybe a good option for you depending on the demand and turn around times.