On average, listings lease in the $10's per square foot per year. The Eau Claire region is going through a decline in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 4% decrease in rent.
In the last 90 days, 29 listings have been made available, which means leases most likley are going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,680 sqft. Most properties in this market are around 2 floors. Most buildings in this market were built in 1978 and are Class B.