How to make bubble tea - the "real" (tea-less) version? Is there a way to create the powdered flavoring?
You can try finding the powder at an Asian grocery store.  The one I frequent has a section of powders that seem like they might be geared more toward a consumer than a restaurant.  I just checked: it's a one pound bag.  I was able to buy just the one bag, but it was a while ago, so I don't recall the price.  According to the bag, the ingredients are Non-dairy creamer, (whatever flavor - I have strawberry and almond) powder, glucose, and coloring.  Even though it says it has glucose, you're still supposed to add sugar according to the directions (and it definitely needs it).

As for creaminess, you might consider trying milk/soy milk/almond milk, etc. instead of water.  When ever I've made it, it turned out much better like that.  The directions call for extra non-dairy creamer, but the recommended amount didn't seem to be enough, so the next batch, I just made it with soy milk (no particular reason for soy over regular: I just don't have regular on hand).