Who pays for a dna test to be done?

my ex thinks he isn't the father of my baby and wants a dna test to be done. I have no problem with it but he says I have to pay for it. In the state of Illinois who has to pay? I have a medical card & I recieve food stamps. I am not on welfare or WIC but my ex thinks I should be. Will I have to pay for the test or does the father?