The Signature at ORD is very expensive, but it's your only option. Went in there in an Archer late at night last year, and from memory here are the fees they charged:
Landing Fee: $9
Handling Fee: $22 (waived with fuel purchase, but 100LL is probably around $5/gal nowadays)
Security Fee (If you want to leave the Signature building): $50
I might be forgetting something, but just be prepared to pay a lot. In my opinion it was worth it for the experience of flying in to the world's busiest airport.