Compared to the rest of the Seattle Metropolitan Area market, the Mercer Island region has more expensive rates, and you'll have to negotiate above asking rent to be in this hot submarket.
In the last 90 days, 1 listings have come on the market, 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 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 1,460 sqft. Most properties in this region are close to 2 stories. Most buildings in this market were built in 1979 and are Class A.