The typical asking rate per listing is in the $20's per square foot per year. The Beaverton submarket is going through a a rise in rates. In the last 3 months, the median rate went up $1 per sqft per year. That's a 7% increase in rent.
Compared to the rest of the Greater Portland market, the Beaverton region has less expensive rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 70 listings have been listed, so you'll want to check back regularly for new listings. 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 1,990 sqft. Most properties in this market are around 1 floors. Most buildings in this area were built in 1987 and are Class A.