i have a recipe i love, it includes pyrat rum, maine root ginger beer (it's kinda important that you get a spicy ginger beer and not a sweet one, this only comes from trial and error of different brands). target brand is good in a pinch. i use maine root ginger beer, $7 a 4 pack. cruzan black strap rum is a staple. a wedge of lime and a couple of diced jalapeno.
that's how i do it.
if you tell me the brands of ginger beer you're dealing with i can tell you which are good, suck, etc.