I'm sure price will vary from country to country, over here its not cheap either compared to other brands of foods, but so far Massivore and NLS have both worked for my puffer and other fish large enough to eat the pellets...
If you also look around here, some people even claim that NLS has helped bring out the color of their fish more, although on a personal level, my experience has been the color of my fish seemed to stay the same regardless of diet...
Anyway, while i'm sure there is probably nothing wrong with the algae wafers, you may just find it has more of a veggie based content compared to the other two products, which for a carnivorous fish, which may not be a bad thing?
-EDIT-
I should also clarify that i'm NOT saying you must feed pellets on top of their existing diet, but just if you wanted to add to his existing diet you could throw in some pellets to ensure you fish gets all the vitamins etc it may need and miss from the other foods you feed your fish currently...