MRI Options in Chicagoland Area

My doctor is at Northwestern and referred me for an MRI. The total cost is like $4K and my insurance covers about $2500 of it, leaving me with a $1500 bill. Does anyone have experience with other MRI places that don’t charge as much, in or near Chicago? I’d be happy to pay for it out of pocket if it’s less than $1K, I’d really just rather try shopping around ahead of time.