Are they? 
 
Cheers

The Triple Bonus Pack is only worth getting if you want the memory lamp.  The Killer Machine ring isn't really essential but I suppose it helps in some places.  The additional dream is neat too, but it's only worth it if you really liked the dreams.  Basically, if you want to be able to watch any cut scene from the game at any given time then it's worth the $2.50, although I personally feel like it should have been included in the game in the first place.
 
The Seeker of the Deep dungeon is worth getting if you're really into the game, but you will have to be ready for some extreme preparation.  The boss in this dungeon is hard as hell and you will have to do a lot of skill/level grinding to get adequately prepared to take him on.  There are also achievements for every 5th floor all the way up to floor 25, so that's an easy 50 points, but the other 50 you get from the boss will take a lot of time and hard work to get.  Definitely worth getting if you're a hardcore RPG player and you like Lost Odyssey a lot.
 
It's also worth noting that you cannot use the memory lamp until you get the Nautilus, and you cannot access the bonus dungeon until disc 4.