I have the "new" versions (silver & red) of the Double Riders in that same series (I think it's the same one, they're on kind of greenish cards?) and I left them sealed. Mostly out of space issues.
If the package is really beat up, you might want to open them up, but otherwise, I think they have the sort of packaging where they still look pretty good in it.
Banpresto toys are funny, they can be expensive when they are new (since you either have to win them from the prize machines, or shell out the dough to buy them at a store after someone else already bought them in bulk) but they can go down to dirt-cheap after a while, because they make so many of them and there's almost always surplus*. Case in point, those jumbo-sized figures they do for all the current shows. I saw TheBee, Drake & Sasword for barely 500 yen each last time I was in Japan, while newer ones were still going for 1500~3000.
*Almost, except for the ones I really want, like the original Rider "home/office supplies" they did recently. I want my Shocker pencil case baaaaaaaaaaaaaaaaaaaaaaaad.
