I'm not opposed to making them cost similar to pillars, but I just don't think it's necessary.
Pillars are the building blocks of decks. Most decks need them, and any deck that DOES won't work without them. That's why they're cheap: so people can make decks, since the absence (or not being able to afford them) makes all decks unviable.
However, pendulums are a bit different. Like other cards, a deck can be made without them. If you don't have 6 dragons needed for a deck, you can get away with 3-5 and replace the other cards with something different. The deck would still work and you could play all your other cards. With pendulums, you can just buy half pillars of one element and half of another, and get the same quanta usage just less consistent.
Thus, pendulums have more in common use-wise with other cards rather than pillars. They aren't necessary, and though do improve a deck, aren't needed. So I think they should cost the same as the other cards.
Again, though, I'm not opposed to making them cost less. Wouldn't make one bit of difference to me.
