Most listings are in the $10's per square foot per year. The Oregon City submarket is experiencing a an increase in rates. In the last 3 months, the median rate went up $16 per sqft per year.
Compared to the rest of the Greater Portland market, the Oregon City region has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 3 listings have been posted online, which means new availabilities are probably going fast. You'll want to be prepared to make an offer immediately. About 33% of the office spaces in the Oregon City 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 200 sqft. Most properties in this region are close to 1 stories. Most buildings in this region were built in 1991 and are Class B.