This is truly CHICKEN MONEY — money you cannot afford to lose. You MUST put it in a money market deposit account or CD at the bank. Any bank. CE should be maximum one year maturity.
I know you will be earning minimal interest, but that’s not the point. You won’t lose ANY money!
PS Good move not to buy in the city now. Property taxes are going nowhere but up. And I’m betting that by the time you retire Il residents will pay state income taxes on thei retirement benefits — currently un-taxed.