I see you are in the NW suburbs of Chicago. So am I and I can tell you that referral bonuses are legal in IL!
Residents of Illinois can and do participate in the referral program.
Which states are eligible for the Program? An Eligible State is any state that permits rewarding Members for their participation in the Sharing the Magic Program. Currently those states are: Alabama, Arizona, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Iowa, Kansas, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Rhode Island, South Carolina, South Dakota, and Wisconsin. Puerto Rico is also an eligible jurisdiction.
Under the Member Privileges section of the member site all the details are outlined.