Thanks for the heads up! I've seen their cables mentioned before, but never noticed that option to add a mic. In addition to the one you linked to, he has some other cables also for sale at different price points. I found it interesting that he offers a significantly cheaper mic upgrade for his higher tier cables (pricewise). These seem to be designed for the stock TF10 plug though, but I'll inquire if they can make it compatible for customs.
crystal
34.90 + 49.90 mic = $84.80
pearl
46.90 + 49.90 mic = $96.80
diablo
69.90 + 19.90 mic = $89.80
silver
119.90 + 19.90 mic = $139.80
Prices are steeper than I had hoped, but there doesn't seem to be any other alternatives. If they can make it compatible for customs I may still bite though, and so far leaning towards the "Diablo" cable, unless "Silver" is worth the upgrade. We'll see.
crystal
34.90 + 49.90 = 84.80
pearl
46.90 + 49.90 = 96.80
diablo
69.90 + 19.90 = 89.80
silver
119.90 + 19.90 = 139.80