Most listings are in the $20's per square foot per year. The SeaTac submarket is seeing a a boost in rates. In the last 3 months, the median rate rose $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 discounted submarket.
In the last 90 days, 5 listings have been made available, which means spaces are probably leasing quickly. 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 find a shorter term or below market rent. 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 3,420 sqft, there are still 0 listings below 2,000 sqft. Most properties in this market are approximately 3 floors. Most buildings in this market were built in 1979 and are Class B.