I've never seen them sold whole. The fruit doesn't keep long, and it would need to be frozen in the States or imported by air. Even in Brazil it was always a juice or frozen outside of the regions where it's indigenous. I've had it in the US a few times, at stores selling exotic juices (it was a mom and pop store like Jamba Juice in San Diego).
As to the energizing factor, it's overrated in my opinion. It's packed with calories and fat, so it's an energy food in the same way that granola or even snickers is considered an energy food.