Most listings are in the $20's per square foot per year. The Beaverton submarket is going through a a boost in rates. In the last 3 months, the median rate rose $5 per sqft per year. That's a 25% increase in rent.
Compared to the rest of the Greater Portland market, the Beaverton submarket has lower rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 65 listings have been posted online, so you'll want to check back regularly for new listings. About 2% of the listings in the Beaverton are subleases, so you will probably have to focus your search on direct office leases. 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 2,120 sqft. Most buildings in this area are around 1 floors. Most buildings in this market were built in 1987 and are Class A.