There's a US based seller with QSFP28 100G DAC cables (PDF datasheet) selling a lot of 5 for $50 (best offer available) with free shipping:
From what I can tell from the datasheet, they're 1m cables, but the Molex part number (1002973003) also seems to refer to 3m cables?
$10/each seems like a pretty good price for QSFP28 DAC cables rated for 100G. Seller currently has more than 10 lots available.
I think this is a good deal, but someone can correct me if I'm wrong and QSFP28 cables are actually always this cheap. I don't have anything that can barf packets at 100G

From what I can tell from the datasheet, they're 1m cables, but the Molex part number (1002973003) also seems to refer to 3m cables?
$10/each seems like a pretty good price for QSFP28 DAC cables rated for 100G. Seller currently has more than 10 lots available.
I think this is a good deal, but someone can correct me if I'm wrong and QSFP28 cables are actually always this cheap. I don't have anything that can barf packets at 100G