The typical asking rate per listing is in the $20's per square foot per year. The SeaTac region is experiencing a a rise in rates. In the last 3 months, the median rate went up $22 per sqft per year.
Compared to the rest of the Seattle Metropolitan Area market, the SeaTac region has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 5 listings have been posted online, which means new availabilities are probably going fast. You'll want to be prepared to make an offer immediately. About 120% of the office spaces in the SeaTac are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
Even though the median size is 4,190 sqft, there are still 0 spaces below 2,000 sqft. Most buildings in this area are around 3 stories. Most buildings in this market were built in 1979 and are Class B.