How do I move all my stuff, my car, & my cat 3000 miles in the most inexpensive way?

and very, very soon.
I’m moving from Michigan to Oregon and I’m trying to take everything in one trip. I have a car, but need to return it to Michigan after the move. I’ve minimized my stuff the best I can, but I also have a cat so I need the car to get there, what’s the best/cheapest way to get all there and bring the car back?