It really comes down to what kind of finish was on it before, what kinda of finish they want on it now.. And how much prep work you have to do. If you can do something as easy as a putty fill, clean, screen and recoat, it wouldn't be bad, but getting into sanding takes a little... ok a lot more practice. Up until recently we refused to recommend anybody in our area because they would leave the floor a wreck: lots of dust in the finish, chatter marks from the belt sanders, houses left unfinished for weeks. We finally have someone from out west who grew up in the refinish biz and does an amazing job but he's been doing it for 30 years.