I have some Bodum filters like that one, they work great. You can buy a plain filter from Tea Gschwendner.
http://shop.tgtea.com/store/category...-%26-Infusers/
I like the Magic Tea Maker and the Teafilter large. The Magic Tea maker can be used at any desk or kitchen. It works great, I have the Teavana version, and makes great tea. The filter is portable and can be used in any mug so you are not restricted in the size mug you use to make your tea.