On average, listings lease in the $30's per square foot per year. The Arlington submarket is seeing a a rise in rates. In the last 3 months, the median rate rose $12 per sqft per year. That's a 60% rise in rent.
Compared to the rest of the Seattle Metropolitan Area market, the Arlington submarket has less expensive rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 0 listings have been made available, which means leases most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About Inf% of the listings in the Arlington 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 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 2,000 sqft. Most properties in this region are close to 1 floors. Most buildings in this market were built in 1998 and are Class B.