Mike, The range starts as low as $2.32 psf/yr up to $15 psf/yr for smaller spaces. Most of the medium size spaces go for the $4 to $7 range psf/yr net.
While the question seems simple, the answer requires much more inquiry to determine what amenities you need, how much space you will require, type of loading requirements, your budget, and length of lease.
\I have been a commercial real estate broker in Joliet since 1993 and can be of tremendous help to you with your search. Call me directly and I will meet you at your office. 815-791-7467