Ah yes, good old "blister packaging" as it was called. I don't think there's any good way to get it open without using scissors and carefully cutting along the top edge so as not to nick the cardboard insert.
That said, and I'm not trying to be a downer, to my untrained eye I'm not sure what makes it very precious. I bought packs similar to these back when the DS was new (granted 3rd-party and not officially Nintendo branded, but still). I wouldn't feel too guilty about cutting it open, as I doubt this pack will be a collector's item.
I can see the styluses being worth something, as Phat-sized ones became difficult to find once the DS Lite came out. Maybe the car-charger too since the charging port changed with the DS Lite as well, though for that you could just get a generic USB charging cable. The headphones look generic and the game cases are a dime-a-dozen. The overall DS case could be good, though I'd have to hold it in my hand to make a better judgment there.
