Compared to the rest of the East Bay market, the South Berkeley region has higher rates, and you'll need to pay a premium to be in this hot submarket.
In the last 90 days, 4 listings have been made available, which means leases are probably going fast. You'll want to be prepared to make an offer immediately. About 50% of the available leases in the South Berkeley are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
Even though the median size is 4,000 sqft, there are still 0 leases below 2,000 sqft. Most buildings in this region are approximately 3 floors. Most buildings in this area were built in 1971 and are Class B.
Not much of the real estate is used for commercial space, so it might be hard to find office space. Health care is the dominant industry in this region. Most of the folk of South Berkeley work from home. Commuting between 20 and 25 minutes a day is the norm for those who opt to reside in this part of town.