I saw a few bottles ( different brands) at William Sonoma, about $26...on the other hand, it's not the oil you bake/fry with, so i assume it'd last for a long time...
Trader Joe's has it for about $9 a bottle, I believe. I don't think it's 100% pure truffle oil--I think it's olive oil with truffle extract or something, but I've tried it and think it tastes just about the same.
I believe there's white and black truffle oils, and white is the more "universal" flavor-wise.
A chef friend claims no truffle oil is natural - they're all basically artificially flavored/scented olive oil. I guess it's too volatile or something. It sketched him out so he actually took a dish off his menu because he didn't want to use a "synthetic" ingredient.