Most listings are in the $0's per square foot per year. The Burien region is experiencing a decline in rates. In the last 3 months, the median rate fell $31 per sqft per year. That's a 100% decline in rent.
In the last 90 days, 2 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 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 sqft. Most properties in this area are around 2 floors. Most buildings in this market were built in 1979 and are Class B.