The typical asking rate per listing is in the $30's per square foot per year. The Kent submarket is experiencing a a rise in rates. In the last 3 months, the median rate rose $13 per sqft per year. That's a 68% increase in rent.
Compared to the rest of the Seattle Metropolitan Area market, the Kent region has less expensive rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 10 listings have come on the market, which means leases most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 110% of the listings in the Kent are subleases, so you might be able to snag a great spot on a short term. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,330 sqft. Most properties in this market are approximately 1 floors. Most buildings in this area were built in 1986 and are Class A.