I was under the impression that fluoride in tea was mainly a concern in non-organics. I'm sorry I don't have any links or anything, but I thought that the chemical fertilizers used for tea growing contained varying amounts of chemical fluoride and that's how it ends up in the tea. In organic tea this wouldn't be an issue. Fluoride is of course also a naturally occurring substance so we could expect it to show up in all soil and water to varying degrees. If you avoid synthetically fluoridated water and toothpaste I really don't think you should stress too much about the tea. Whole Foods sells a house brand of green and black tea that's actually pretty cheap.
edit (after looking for links) I'm not finding any definitive studies or data in my search, but I keep finding others in agreement. There seems to be a vague "organic should be lower in fluoride" idea out there, but no data to be found. My personal reasoning is this: Tea plants uptake fluoride more than any other plant. Pollution and pesticide/chemical fertilizer use leads to conventionally grown tea having abnormal and unhealthy levels of fluoride. Organically grown tea will be not be exposed to any synthetic fluoride by the farmer. Naturally occurring fluoride in the soil may be present as well as natural or synthetic fl in the water used (to water the plants). If the area is very polluted additional synthetic fluoride could be found in the otherwise organic tea. However, this should still be far less than the fluoride found in non-organics. There may be no way of knowing for sure how much fl is in your cup of tea, but the important message might be to buy the best quality tea you can and imbibe in moderation.