You know, I used to use bird sand when I first got my own bird. I probably used it for 1.5-2 years, but after having two cages for a few months the bill was getting out of hand. Not to mention it would all get stuck to the tray and made for more cleaning. Honestly I have to laugh when I think back how ridiculous. I bet I spent a fortune on it.
Paper all the way! Cheaper, can monitor droppings and fallen foods and in general (as far as parrots go) a lot less messy. I wouldn´t even consider anything other than paper now.