A lot of instructors charge per lesson rather than by the hour, how long the lesson takes is sort of up to you. I get the feeling many of them don't watch the clock religiously and hit you for every minute.
I think it's realistic to expect around 100 bucks per lesson from a certified instructor. Anyone charging less than that is probably just a good local... which doesn't mean they can't help you, but it's kind of a gamble.
Most Certified instructors do not charge $100 an hour or per lesson. I don't think it's fair to label us "just a good local". That's certainly true for some of us (maybe me!), but I for one, am always reading and watching, and working to improve my teaching skills.
I clearly don't play as well as I did when I was 50 (20 years ago), and for this reason some folks don't think I can teach. They don't consider the fact that I'm a cancer and stroke survivor, with emphysema from second hand smoke.
So I currently charge $20 an hour or $30 for two hours (and don't charge extra for overtime). I offer even more discounts to teach couples or teams. I'm not a Master or Advanced instructor. I could never afford that. I don't teach one pocket because while I love the game, there are many instructors who know the game better. I don't teach 3-cushion for the same reason. But I've gotten good reviews from students for what I do teach. My specialties are 8-ball and 9-ball strategy and cue ball control, but I always focus on basics.
My fees are low because of the economy, and I don't want to see pool become a game of the wealthy only.
I've heard Ralf Souquet, a top pro who's won many majors, charges 100 euros (around 130 bucks an hour). But that was a while ago and his prices may have gone up since then. I've gotten quotes from 2 other known pros on this site, one was $100 and the other was $150.
TLDR: be leery of anyone charging less than 100. 100-150 is reasonable. I personally wouldn't pay over 150 unless it's a widely known champion. Good luck with your search. You may need to travel and that adds to the cost.