Most listings are in the $30's per square foot per year. The Greater Portland region is experiencing a a boost in rates. In the last 3 months, the median rate went up $4 per sqft per year. That's a 14% increase in rent.
In the last 90 days, 541 listings have been made available, so you'll want to check back regularly for new listings. About 2% of the available leases in the Greater Portland are subleases, so you will probably have to consider a longer term lease. 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 2,270 sqft. Most properties in this market are around 2 floors. Most buildings in this area were built in 1985 and are Class A.