My instructor charges $55 an hour (she offers hunter/jumper and dressage).  I ride her horses. At some point in the near future, I will be hauling my horse over but the price will stay the same. Prices here vary with instructor's qualifications as well as location. My instructor's barn is in a very affluent suburb. If you drive 30 minutes west, the prices drop to around $45 an hour.

I have no idea about western lessons.  I don't know of any barns that offer them.  I am in metro Atlanta.

Somewhere - behind the rider you've become, the long hours in the saddle,
the ribbons you didn't win, the falls you've taken, the tears you've cried,
and the horses you've given your heart to - is the little girl who fell in love
with the sport and never looked back. Ride for her.
-- Author Unknown