This weekend, I placed on order with Topps during their memorial day sale. I was able to duplicate the same issue I had when I (thought I had) placed my binder pre-order. I logged into Topps.com with my account. Added the items to my "bag" and proceeded to the checkout. At checkout, there were two options. Normal checkout and Paypal checkout. I used the Paypal checkout. This took me to Paypal where you log in. The total is shown, but I noticed there was no shipping fees. I didn't give this a second thought on the binder pre-order since it was supposed to be free shipping. I completed the checkout and received a Paypal notification. There was no order number on the PayPal notice. When I checked the Topps site, the two items I attempted to order were no longer in my bag, but there was no order shown on the Topps site. I waited several hours to see if I received any notifications from Topps. When I logged back into Topps.com, the items were in my bag again.
I then went through the process again this time choosing the normal checkout. When payment type was selected, I choose Paypal. This "path" through the checkout worked fine. After logging into Paypal during checkout, it showed the correct total including shipping this time. After finishing the checkout, I received both Paypal and Topps notifications.
It appears to me there is some disconnect between Topps and Paypal when the Paypal checkout option is selected. I would recommend avoiding it.