A cool venue that I would have loved to use but was too small for my wedding was the Detroit historical museum. They can fit 150 and it's byo caterer. Since it's a less common venue it might still be available in October.
To be fair: My best friend is the event planner for a catering company and I work for them sometimes. I just worked a wedding at the Packard Plant last weekend so I second that facility! It was very cool! ETA: she also catered a wedding at the Detroit Historical Museum that I attended. Pro tip: only rent the basement, it's way cheaper than renting the whole building and your guests still get full access to the museum.
We also looked at:
Royal Oak Farmers Market 30 North - downtown Pontiac
Crofoot Ballroom ($500 additional for own caterer) Great Lakes Culinary Center in Southfield (only $500 to rent) Rust Belt Russel Industrial Center
Re: Detroit Venues
We also looked at:
30 North - downtown Pontiac
Great Lakes Culinary Center in Southfield (only $500 to rent)
Rust Belt
Russel Industrial Center