On average, listings lease in the $10's per square foot per year. The Warren region is going through a an increase in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 4% increase in rent.
Compared to the rest of the Metro Detroit market, the Warren submarket has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 64 listings have been posted online, so you'll want to check back regularly for new listings. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,400 sqft. Most buildings in this area are around 1 stories. Most buildings in this market were built in 1970 and are Class B.