can I come straight to the theater to purchase tickets to avoid the ticketmaster fee?

Yes but I believe there is still a fee

Theres a fee but not as much as Ticketmaster

I always get the tickets before hand so I can get the seats I want. You don't have to use Ticketmaster. There are at least 4 other sites to choose from https://www.google.com/search?q=fox+theatre+detroit+tickets&oq=fox++theatre+detroit+tickets&aqs=chrome..69i57.27409j0j7&client=ms-android-att-us&sourceid=chrome-mobile&ie=UTF-8

Lovell Sewell there's no fee and also just to remind you they don't give out paper tickets any more they send them to your phone to get scan upon entrance

You can purchase tickets at the box office but I'm not sure there won't still be a fee