I use both. It all depends on what I'm tying. Neither is a good substitute for the other. Don't paint yourself in a corner. This hobby isn't about saving money. That being said, if Bucktail is what you have, I'd ty a bunch of clousers.

Do do you plan on dyeing the Bucktail?

Marabou isn't expensive. I'd buy white and use markers to embellish if I didn't want to buy a variety of colors.