Just wanted to share with the OP that I found a discount code on mousesavers.com rental car page for Dollar and Thrifty that saved me a good bit of money for my one way minivan rental. I am renting at SFO and returning at LAX for a 12 day rental, the discount made it $100 less than my original Budget reservation in which I had to pay cab fare to the off airport location, return the car in Anaheim and purchase a shuttle for us to get to LAX.
I dont know if that helps you, but I was thrilled.