It all depends on how far west you travel. It also depends on the age of the building. The rental market has really taken a hit lately and since its become almost impossible for people to get loans on store fronts, land lords are more flexible on price. A ballpark figure if your staying west of Damen I would say around $15-$21 a sq/ft. In order to get a better figure I would need to know more about what you are looking to do.
Americorp Real Estate
Brokers Associate, e-PRO