You might try Enterprise Rent-a-car, and I would recommend calling a location rather than using the website. I was able to rent a car tomorrow DSM-SUX one way at the regular rate of $30 + a $40 drop charge. Total with tax will be around $83. This is without insurance so it might not be good for a foreign traveler, but a good heads up. As a business traveler I don't usually consider Enterprise but I thought I'd check it out today. I saved $100 over the Hertz rate.