need a root beer recipe

Most homebrew shops will have a concentrate for root beer. I have never used them, but I imagine that they're what you're looking for. If you want to go the root method, try picking up "Homemade Root Beer, Soda & Pop" by Stephen Cresswell. I've done root beer from this book and it came out pretty well.

I don't remember the exact recipe that I used, but I used sarsparilla root, juniper berry, star anise, wintergreen and a few others that I don't honestly recall. I purchased the bulk herbs from Stony Mountain Botanicals

A keg system for force carbonation works well, though you don't need it. You could use plastic bottles and yeast to carbonate. You need to refrigerate it to stop the yeast. Supposedly, the yeast won't take off because there are no nutrients to sustain them, but I wouldn't take that chance.

I used the extract to make rootbeer once. It was the best stuff I ever tasted. The only problem is we forgot about 6 bottles that were in the fridge in the garage. After about 3 months they exploded so violently they almost trashed the inside of the fridge....lol. It was a mess. But really, those extracts make a very decent soda and under normal circumstances I doubt they would last 3 months. I'm making raspberry soda right now, got about a week to go.