Carl T. Griffith gave his 1847 Oregon Trail sourdough starter away for free to anyone who asked or sent a self-addressed stamped envelope; he passed away in 2000 but his friends are keeping the tradition (and the sourdough starter) alive.
If for some reason you'd like your sourdough starter younger or slightly more international, this site will sell you cultures from twelve different countries from Finland ("The wonderful and distinctive flavor and aroma it imparts are truly "indescribable".) to Egypt ("The bakery where this sourdough was found dated straight back to antiquity and was literally in the shadow of the pyramids. This culture could be the progeny of the one that made man's first bread and is similar to the one we used to recreate that first bread in Egypt for the National Geographic.").
[via Boing Boing]