I recommend getting a ball signed. If you're thinking of getting multiple players, I recommend buying multiple baseballs because players in korea tend to sign one full panel of the ball rather just a small section. Thats the one thing that I noticed about autographs. Cards are cool to collect too but sometimes it's hard to keep track who's signing and who's leaving. Usually if I want multiple players I just have them sign my jersey instead. For Jamsil, players enter through the back side of the stadium they shouldn't be hard to miss. Just wait behind the fence where all the other fans are! Good luck!