Compared to the rest of the Chicagoland market, the Oak Forest submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 3 listings have been posted online, which means new availabilities most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 630 sqft. Most properties in this area are around 1 floors. Most buildings in this market were built in 1978 and are Class B.