i was just wondering, is it possible to buy a b-foot seperate and just add it on to ur flute, instead of having to buy a whole new flute? and if you can, who sells them? thanks!

yes it is possible
your local instrument store should have them, if they dont then they should be able to order it

The key to buying a new footjoint is to make sure that it is compatable with your current flute. I know most Japanese makes are compatable with each other ie. Miyazawa usually fits Pearl ~Yamaha ~Muramatsu. Geminhardt and Armstrong are usually interchangeable since they are effectively the same company.
I say "usually" because every flute is different and you may need adjustments on the tenons of the flute and/or footjoint to make (them fit together.)

If you want a new footjoint, it`s probably best to find one the same brand as the body of your flute to minimize the chance of them not fitting. This won`t always be possible, in which case make sure you know the thickness of the wall of your flute so you can match that to a footjoint that fits if you have to order it.