I have refinished floors in many houses and while I don't think it's a big deal I can certainly understand how it may be for some people. It is VERY labor intensive. I can say "just rent a drum sander and..." without telling you that the sanders weigh about 130 pounds.
I don't know how strong you are but a lot of fols may not be able to lift this in or out of their car/truck.
It does take about a week to do it right and if you are living in the house at the same time, even longer since you have to move furniture from one room to another and put dust shields to prevent the house from being flooded with floor dust.
In Atlanta, Georgia, I have seen between $1.50 and $4.00 per square foot with no real difference in the quality between the jobs. That is to say that a $4.00/ft job is not necessarily any better than a $1.50/ft job.
Normally, I encourage people to do as much as possible but on this kind of thing, unless you have someone you trust helping you for the entire job, your time may be better spent interviewing and more importantly LITERALLY looking at the person's work in a recent house. Most reputable floor refinishers are proud to show off their work so do go by whether or not you fell warm and fuzzy with the floor guy. Also, talk to the people (his past customers) and ask them if they are happy and to what degree the job was intrusive to them. This is important if you are living there as you want to see how clean he was.
Measure the floors to be done with a good long tape measure and start calling people and asking per square foot charge. Then see if you can look at there work.