Most listings are in the $20's per square foot per year. The South Plainfield region is seeing a a boost in rates. In the last 3 months, the median rate went up $5 per sqft per year. That's a 25% increase in rent.
In the last 90 days, 8 listings have been posted online, which means listings most likley are going fast. You'll want to be prepared to make an offer immediately. 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 1,630 sqft. Most buildings in this market are close to 1 floors. Most buildings in this area were built in 1989 and are Class A.