On average, listings lease in the $20's per square foot per year. The SeaTac region is seeing a an increase in rates. In the last 3 months, the median rate rose $26 per sqft per year.
Compared to the rest of the Seattle Metropolitan Area market, the SeaTac region has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 5 listings have come on the market, which means spaces might be leasing quickly. 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 1,300 sqft. Most buildings in this market are approximately 3 floors. Most buildings in this market were built in 1979 and are Class B.