You cant use Google Checkout on items that is preorder. Only once it is in stock and available. It shows the Google Checkout info saying you can get it for $43.99 but if you look to the right, the Google Checkout button is greyed out.
Ineligible Items - Certain items are unavailable for purchase using Google Checkout. In addition to the items listed in Google’s Prohibited Products Policy, there are certain other items that are currently unavailable or that may become unavailable for use with Google Checkout (including, but not limited to, cell phones, market place items, digital downloads, magazines, extended warranties, pre-orders, on order items, items requiring the collection of Ca recycling fees and other special items). When your shopping cart contains items that cannot be purchased using Google Checkout, the Google Checkout button will appear grey and you will be unable to checkout using the Google Checkout process. The following is an example of what the Google Checkout button will look like when you have ineligible products in your basket.