Most listings are in the $30's per square foot per year. The Bethesda submarket is going through a decline in rates. In the last 3 months, the median rate fell $9 per sqft per year. That's a 20% decline in rent.
Compared to the rest of the Washington D.C. market, the Bethesda region has greater rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 23 listings have come on the market, which means listings most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 83% of the available space in the Bethesda 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,400 sqft. Most buildings in this area are around 10 stories. Most buildings in this area were built in 1980 and are Class A.