Most listings are in the $40's per square foot per year. The Mercer Island region is going through a a boost in rates. In the last 3 months, the median rate went up $45 per sqft per year.
Compared to the rest of the Seattle Metropolitan Area market, the Mercer Island submarket has higher rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 1 listings have come on the market, which means office spaces might be 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 1,460 sqft. Most properties in this region are close to 2 floors. Most buildings in this market were built in 1979 and are Class A.