Oh HELL yeah! This game is so worth it, and you can pick it up for not too much. I don't know where you live, but try amazon or Ebay.
That would be my first response.
On the other hand, tri G is gonna be awesome as well, but I believe - NOT SURE! - that it's kinda similar to portable 3rd, so you might get a PSP, and freedom unite and import portable 3rd. The biggest disadvantage is that maybe tri G is way more awesome and that portable 3rd is Japanese.
The biggest advantage is that you can play it now and you can get a PSP for around 100 dollars/80 euros while the 3DS is way more expensive.