There are so many factors that come into play (industry type, education level, # of employees, etc.) when determining the salary of an Office Manager, but on average, the low end would be 50K.
That all depends on which company the office manager works for. If it's a company in the private sector, it could be either tiny tiny amount (if it's a small company) or a nice big wad with a big successful company. In the public sector, you would earn less than average. I'm talking about UK companies here, you might be from USA in which case, I have no idea!
An office manager makes well over 8,000 dollars a year
An office manager makes well over 8,000 dollars a year