PM Office

After months of leading our Project Management Office, I have been recently asked to become Manager. I have been asked to research and submit a salary for my position. I have my MBA and 3 years of Management experience, but havent the slightest clue as to where to start researching. I have also been asked to Manage another office roughly 50 miles away so I would be doing 2 days in one office and 3 in another. Any help would be appreciated..

Experience: MBA + 3 yrs Management
Position: PM Office Manager for 2 offices 50 miles apart in the Arizona\Phoenix Area
Total No. of Emp.: 20

If anyone knows of a formula or justifiable way of showing salary requirements, I would appreciate it very much.

Thank you in advance…