I saw one at Academy Sports & Outdoors (if you live in the south). I'd also check Gander Mountain and REI, though they'll charge more. Here's a good looking one similar in size to one I picked up locally.
http://www.getgeargooutside.com/73230.html
And here's a link for one by Alladin, though mine is wider and shorter like the one above, making it easier to eat from.
http://familyonboard.com/insulated_t..._tumblers.html