If you are in the US, is it possible to pay the driver on delivery with cash or personal check? I've made a UPS account and entered payment details, but I see no way to assign the shipping invoice to my account for online payment.
Yes. Or at least I did that with my last S9 (so it was almost two years ago already). I spoke with a UPS customer service person about my Z9 shipment, he said they could determine the price after it was landed in the states and through customs on this end. So basically by the time it hits the lower 48 (if that's where yours is going). So you should be able to call and find out exact amount in the 12-24 hours before it actually arrives and then give the driver a check for that amount.
Just for the record, I was actually able to obtain a refund on my payment on that S9 simply by calling their brokerage people and giving them a bunch of tracking numbers for previous bitmain shipments where I had not been required to pay a fee. I have literally never actually paid a fee on a miner import before. But it was a such a pain in the arse I am thinking I'll just suck it up on this Z9 and not complain about it.