Most listings are in the $10's per square foot per year. The Mentor region is going through a a rise in rates. In the last 3 months, the median rate went up $16 per sqft per year.
In the last 90 days, 30 listings have been posted online, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 97% of the listings in the Mentor are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 800 sqft. Most buildings in this market are around 1 stories. Most buildings in this region were built in 1988 and are Class B.