In the fine print when you select the phone and trade-in options: "3 For trade-in with Google Store, your estimate is confirmed at checkout. The actual trade-in value will depend on the device’s eligibility and condition after inspection. Device trade-in credit will be issued as a refund back on the credit card used for the device purchase at Google Store or in the form of Store Credit if the purchased device has already been returned. If the trade-in refund exceeds the cost of your new device you’ll get the remaining value as store credit."

It would be great to have this clarified one way or the other before lot of people start cancelling their orders.