You should consider making your own cola. It's easy, and very rewarding. Recipe mentioned in my other comment [1].
Incidentally, there are some very good "alternative" colas. My favourite is Fentimans' Curiosity Cola [2], which NY Times once described as "the world's best cola", and which is made with a small amount of fermented ginger (fermented juices is their thing). I also really like Boylan's Cane Cola [3].
Fentimans' sounds awesome. I've had a lot of other cane sodas like Boylan's. My kids and I used to raid Bevmo's soda aisle once a week to try new things. That gets expensive though. Passover Coke is nice and cheap by comparison. I never thought about making my own. Maybe I'll give it a try.