Compared to the rest of the Chicagoland market, the Humboldt Park submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 4 listings have come on the market, which means listings most likley are leasing quickly. 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 1,300 sqft. Most properties in this region are around 3 floors. Most buildings in this area were built in 1950 and are Class B.