I've heard of programs where someone needs a car moved from point a to point b. a company arranges for transport by finding someone to drive it there. The company gets a fee from the owners of the car for dealing with moving the car, and the person who drives the car gets to drive the car for no rent, but has to pay for gas. Essentially the company is a matchmaker between car mover and car owner.
No idea if it's legit, how to locate one etc, but you could do a search and see what turns up.
Also, sometimes car rental agencies need cars moved from one place to another and will therefore rent cars out for super cheap if you happen to be going on a 1-way trip where they need the car to go.
So you could do that one way, and either fly (one way tix may be in your budget), take a bus, or take the train the other way.