A pro would prob charge an arm and a leg. A geek who knows what they're doing and has the tools, a lot less.
Most sparkies could do it, probably be best to get a quote.
If all the cable run is Cat5/6, then all they need to do is punch it correctly at each outlet, and put in a patch panel. The patch panel is usually the most time consuming item to do depending how many ports you have. (I have nightmares over the one I had to do years ago for a warehouse, 40+ ports, and was my first time setting one up from scratch - pleased to say it all worked fine :D )