The typical asking rate per listing is in the $30's per square foot per year. The Mukilteo region is going through a an increase in rates. In the last 3 months, the median rate went up $22 per sqft per year. That's a 137% increase in rent.
Compared to the rest of the Seattle Metropolitan Area market, the Mukilteo submarket has higher rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 3 listings have been made available, which means new availabilities are probably going fast. 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 970 sqft. Most buildings in this market are close to 2 floors. Most buildings in this area were built in 2001 and are Class B.