Acai berries are the small, dark purple fruit of a palm tree native to the Amazon. They don't travel well fresh, so outside South America you'll almost always find them frozen as puree, or dried and ground into powder — not whole.
What you're actually buying
Frozen acai puree packs are the closest thing to fresh — usually sold in flat sachets meant to be blended straight from frozen with a little liquid. Acai powder is more shelf-stable and cheaper to ship, but it's a processed product, so check the ingredient list for added sugar before assuming it's plain fruit.
Like most deeply pigmented fruit, acai contains a good amount of anthocyanins — the compounds responsible for its colour. So do blackcurrants, blackberries and dark-skinned grapes, all of which are easier to find and usually cheaper.
Building a bowl that isn't mostly sugar
An acai bowl at a café is often a smoothie base loaded with juice and syrup before the toppings go on. Blending frozen acai puree with unsweetened milk or water, then topping with fresh fruit and a handful of chopped dates instead of granola or honey drizzle, keeps the sugar closer to what the fruit itself contributes.
Dates work well here because they're solid rather than syrupy — you taste them as a distinct topping instead of the whole bowl tasting uniformly sweet. Piarom dates in particular hold their shape well when chopped cold, straight from the fridge.
If acai isn't available
Acai isn't grown or sold fresh in most of Southeast Asia, and frozen imports aren't cheap. A bowl built the same way with frozen mixed berries or a dark grape puree and the same date topping gets you the same format and a similar deep-purple colour, for less.
For dates to keep on hand for this kind of thing, see the wholesale supplier guide or the iranpiarom.com homepage.