The typical asking rate per listing is in the $10's per square foot per year. The South Portland region is experiencing a decline in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 3% decline in rent.
In the last 90 days, 17 listings have been made available, which means new availabilities most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 6% of the office spaces in the South Portland 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 posted, so finding a space for a small business might be tough.
Even though the median size is 2,730 sqft, there are still 0 new listings below 2,000 sqft. Most properties in this area are approximately 2 floors. Most buildings in this market were built in 1974 and are Class A.