Currently at about 13,000 members and 150-200 new members daily, your advertisement will be seen!
I will post your Chicago/Illinois business in my group called "SELLYOURSTUFF!" for 3 days as a pinned post so that any new or existing members can see it.
I will need a picture that displays your business with any given information that you prefer your customers to see.
For any extensive advertising please message me and we can negotiate a proper price.