It's 2900 yen, and if you live in the U.S. expect to pay about $30 for shipping, which I did when I ordered a book and a CD from them. You should probably get a big order together before you do it, you'll make more of your shipping money. =)
They also have 1 used from some place in Japan, click on the 'new and used' section. It's very easy to order from them, so don't be discouraged if you don't know any Japanese.