For Pre-Orders we always charge the full amount of the order. The reason we do this is because of the high price of the items we sell, taking a $10-$20 pre-order is easy for some merchants, the likelihood of charging a customers credit card who may have insufficient funds, or was not expecting the charge later down the road is usually not a big deal. Once you get into the several hundred dollar range though, that changes greatly.
Rather then take the chance of charging someone when they had forgotten about the order and causing them financial issues, we charge full price upfront. Also, it is against the merchant agreement to hold an authorization for more then 30 days on a customers credit card and the merchant can be subject to steep fines if they do so.
Lastly, we take pre-orders not to fund our purchase (We have already paid for the merchandise well in advance) but to allow our customers to guarantee themselves the product since they do move quite fast at times.
A pre-order can be cancelled and refunded in-full at anytime prior to shipping, as long as the order has not been moved into the Awaiting Shipment status, or has been Shipped.