Compared to the rest of the Seattle Metropolitan Area market, the Sumner region has less expensive rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 4 listings have been listed, which means new listings are probably going fast. You'll want to be prepared to make an offer immediately. 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 1,120 sqft. Most buildings in this area are close to 2 stories. Most buildings in this region were built in 2001 and are Class B.