My contract with Tesla for the Model S shows the Oak Brook store address as the dealership. I believe this will satisfy the IL requirements for the state rebate.
I've applied for the rebate twice in the past 10 years (converted EVs) and have received the $. The last time was 2008. However, as posts have noted above, even in poor financial shape the money seems to be there.
On a another note Tesla owners can qualify for EL plates in IL that cost $35 for 2 years.