On average, listings lease in the $10's per square foot per year. The South Portland submarket is seeing a decline in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 7% decrease in rent.
In the last 90 days, 17 listings have been posted online, which means new listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 18% of the available leases in the South 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 2,100 sqft. Most properties in this region are approximately 2 stories. Most buildings in this region were built in 1974 and are Class A.