Just to clarify, no escrow is taking place on this buy?
Also, shouldn't we do this second buy basing the shipping price on a per-chip basis, rather than a per-order basis? Dividing all fees, including shipping and tarriffs by the 10,000 chips, and rolling it into one easy to calculate per-chip cost should save everybody a lot of headache, and will be more fair for everybody involved.
I'm interested in another 50 chips or so. But I don't want to pay more than my fair share of the freight on these things again, if that can be avoided.
A guy ordering 2000 chips paying the same as a guy ordering 10 chips, is crazy. Assuming 80 buyers like last time, that's .8% shipping per share. Guy one is benefitting from 20% of the order, he should be paying 20% of the shipping, but he's only paying a flat share of .08%.
Guy 2 is benefitting .01% of the order, while paying 8 times his share of the shipping. He should be paying .01% of the shipping costs..

Just take the 782.1btc for the order, add the 2.1btc for shipping, for a total of 784.2. (823.41 Figure in 5% fees ( Divide that number by 10,000, and you get a result of .082341BTC per chip, shipping and fees included.
The tariffs can be divided by 10k as well, for a per-chip cost.
Individual shipping from OP to buyer will be whatever they are. No need to socialize the shipping and tariff costs though.
Also this makes it really easy to calculate how much to send per chip. If I want 50 chips, I multiply .082341 * number of desired chips (50).
50*.082341= 4.11705BTC
On the OP's end, it's also simple. Divide number of BTC sent by .082341 to verify number of chips paid for. Easy peasy!

Should save the hassle of needing to do refunds for confusing over-payments, or any of that. Seems to me that a great deal of the work that JohnK had to put into the last one was figuring out who overpaid, by how much, and why. I know I had trouble figuring out how much I needed to actually send as well.
Just my $0.02. Take it for what it's worth.