I ♥ my employee discount for manga buying, even if the store does accidentally re-order things I special-ordered for myself that no one else on earth not as evil-crack-minded as me will ever buy. Sigh. Anyway, BigWords.com is good for book-bargain-shopping, though most of the time it's cheapest there at Half.com anyway. And I've gotten some ridiculously good deals at garagesalejapan, but you do have to watch the seller feedback and shipping fees.