Most listings are in the $20's per square foot per year. The Middleton region is going through a decline in rates. In the last 3 months, the median rate fell $4 per sqft per year. That's a 15% decline in rent.
In the last 90 days, 17 listings have been made available, which means new availabilities are probably going fast. You'll want to be prepared to make an offer immediately. About 6% of the available leases in the Middleton are subleases, so you will probably have to consider a longer term lease. 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 2,380 sqft. Most buildings in this market are approximately 2 floors. Most buildings in this region were built in 1995 and are Class A.