Nice find, but don't be fooled.
That's actually a series 2 Starter ( but it might have come with series 1 cards).
There was an odd time right around October '08 Spinmaster was having a hard time getting Bakugan out. They took some of the older series 1 packaging and cards they had left over and started packing Series 2 Bakugan in it like the Non-attribute change preyas and especially the Manion and Seige. - so regardless, pretty rare stuff, esp IN package.
The Dragonoid and Serpenoid on the previous post are also from around that time. ( If you notice the Serpenoid has holes in it, meaning it's a newer old style serpenoid. I hate those holes with a passion)
I've been seeing leftovers like these popping up at TRUs. At least the boosters. Which is how I finally got my Trans Darkus Stinglash.
