Yesterday was the American National Day. He was probably not around his computer.
Have you recieved any invoice?
If you have and the shipping is lower than you agreed, pay it. The seller will either settle for that and ship or will cancel the invoice and send you a corrected one.
If the amount is higher than you agreed, try to change the shipping cost. Sometimes this is possible, although most sellers do not allow it, for obvious reasons.
If you have not received any invoice at all, wait until Monday before trying him again. Then send a last email asking for the correct amount. If that is ignored, open an Item Not Received dispute.
