Tales of the Abyss Cheats

In order to unlock the secret shop you must completely fill the collector's book in the game (this requires at least two playthroughs). Upon completion, speak to the man dressed in purple at the library in the Daath church to receive Jade's "Item Collector" title. Speak to the man again with the title equipped and the shop will appear near the Inn in Grand Chokmah.

Abyss Replica Facility

The Abyss Replica Facility is a secret dungeon which can only be unlocked on your second playthrough. To gain access to it, you need to have saved Shiba and completed the Ortion Cavern (East) side quest. Go to Sheridan and talk to the two men in the northwest part of town, then Shiba, and you will be taken to the dungeon.