For collectors who care about long-term investment, following a proper storage method is just as important as the purchase itself
In addition to featuring cards from the main set, 1 in 3 Final Fantasy Play Boosters also contain a card from Final Fantasy Through the Ages
And I believe thats one of the reasons why this collection has grown into what it is today
Also, for most sets, Decipher packed 3 random rares with each starter deck, giving collectors additional reason to purchase them (it was sometimes cheaper to buy boxes of starters instead of boxes of boosters, as each box of starters included 36 rares.) In Battle of Helm's Deep and Ents of Fangorn , Decipher did away with the random rares and instead included 3 predetermined rares, with the idea being to make sure that included rares went according to the theme of the starter deck (predetermined rares also saved printing costs, as it allowed the entire deck to come from one print sheet instead of two.) Fixed rares annoyed players, as it removed the incentive for veterans to purchase the decks, and it reduced the value of the 6 rares affected in each set
With the previous generation, it was always the alternate art Pokemon cards that were the rarest and most expensive