Also a good source for determining PTCGO card values is the In-Game Item Exchange board on the official PTCGO forums. There are numerous "trading companies" who operate in card-for-packs and packs-for-cards. They list the values of most of the various obtainable packs, Ultra Rares, and many Holos, and from my experience serious traders in-game tend to use the trading company threads as general guidelines for card values.
Shaymin-EX reg is listed for around 16 packs on average across the various threads. So if you wanted to go this "company" route, you'd have to send them an offer (in-game or on the forum, depending) for Shaymin with 16 applicable in-game packs. Alternatively, you could "sell" them some cards and use their value to pay for Shaymin.
Shaymin-EX reg is listed for around 16 packs on average across the various threads. So if you wanted to go this "company" route, you'd have to send them an offer (in-game or on the forum, depending) for Shaymin with 16 applicable in-game packs. Alternatively, you could "sell" them some cards and use their value to pay for Shaymin.