AMAZON:How to Preorder USED dvds?
 

Since Half.com is closing down in October, I've noticed Amazon.com offers a pre-order option for used dvds also. However, I can never find the "pre-order it used" button for any of the dvds I am interested in. This is what is states on Amazon's web site:

Pre-ordering items from Amazon Marketplace is easy! Simply locate an item in our catalog that you'd like to buy used and click the "Pre-order it used" button in the blue box directly below the product image.

After you've selected the item, the pre-ordering process goes like this:

You choose the preferred condition of the item.
You set a price that you're willing to pay.
You choose the number of weeks that your pre-order should remain open.
You select the shipping address and choose a credit card.


Does anyone know how this option actually works?