On average, listings lease in the $20's per square foot per year. The Milwaukie submarket is seeing a a rise in rates. In the last 3 months, the median rate rose $23 per sqft per year.
Compared to the rest of the Greater Portland market, the Milwaukie region has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 5 listings have been posted online, which means leases most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 120% of the available leases in the Milwaukie 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 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 1,220 sqft. Most buildings in this area are around 2 floors. Most buildings in this market were built in 1988 and are Class B.