Most listings are in the $30's per square foot per year. The Greater Portland submarket is going through a a rise in rates. In the last 3 months, the median rate went up $32 per sqft per year.
In the last 90 days, 541 listings have been made available, so you'll want to check back regularly for new listings. About 86% of the available space in the Greater Portland 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,960 sqft. Most properties in this market are approximately 2 floors. Most buildings in this market were built in 1985 and are Class A.