Most listings are in the $10's per square foot per year. The Milwaukie region is seeing a decline in rates. In the last 3 months, the median rate fell $7 per sqft per year. That's a 32% decline in rent.
Compared to the rest of the Greater Portland market, the Milwaukie submarket has less expensive rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 2 listings have been made available, which means office spaces 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 690 sqft. Most buildings in this region are close to 2 stories. Most buildings in this area were built in 1988 and are Class B.