Most listings are in the $20's per square foot per year. The Milwaukie submarket is going through a a boost in rates. In the last 3 months, the median rate went up $23 per sqft per year.
Compared to the rest of the Greater Portland market, the Milwaukie region has less expensive rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 5 listings have been made available, which means spaces are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 120% of the office spaces in the Milwaukie are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,220 sqft. Most properties in this area are approximately 2 floors. Most buildings in this region were built in 1988 and are Class B.