We liked this bottle, though our reviewer doesn't drink tea and only used it for water purposes. I concur with some of the concerns posted here when it comes to tea use. Although, you aren't necessarily restricted to tea - you can infuse fruit as well.
http://engearment.com/gear/eco-vessel-boulder-trimax-insulated-water-bottle/
http://engearment.com/gear/eco-vessel-boulder-trimax-insulated-water-bottle/