I just started playing Pokemon Rumble Blast today, when I opened the case, there's a booklet and a information brochure about Pokedex 3D, it said that "free via Nintendo eShop" but I checked the website and I found out that the price is about 15 dollar, so which one is the right price????
The thing that is "free" is probably the outdated Pokedex 3D. Pokedex 3D was discontinued and was replaced by Pokedex 3D Pro (as far as I know). Your brochure is more than likely a bit old, so the information it has is outdated and incorrect.
If you want Pokedex 3D Pro, you'll have to pay for it, unfortunately.
Well, unless you like lots of questions/quizzes about Pokemon, knowing the heights weights, types, index numbers of all .... 649(?) Pokemon, the ability to view short 1-2 second clips, and some American voice pronouncing ALL the Pokemon.... then, no, it's not worth it.