I bought mine from this site.
http://www.handa-accessories.com/accext00.html
They are sold as a set of 4. Honda never offered these splashguards as standard equipment on any model of the 6th gen Accord, but instead they were offered as a available accessory for all models. I have them on both of my 6th gen Accords, they don't really protect that well against splatters, but I think that they finish off the back bumper better.