Most listings are in the $10's per square foot per year. The Brown Deer region is going through a an increase in rates. In the last 3 months, the median rate went up $20 per sqft per year.
Compared to the rest of the Milwaukee County market, the Brown Deer region has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 6 listings have been posted online, which means spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 133% of the available space in the Brown Deer are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,440 sqft. Most buildings in this market are close to 2 stories. Most buildings in this region were built in 1982 and are Class B.