I bought them from a US-based eBay seller that I have personally bought Sennheiser IE8 earphones from before. I have bought several pairs of Sennheiser IE8s from this seller. I kept one pair, and am selling this pair. I can confirm, from the pair I kept, that these earphones are legitimate.
If you want, I can carefully open the box, burn them in for a few days, and then compare them against my friend's pair.
However, for me to do so, you would have to pay me under the condition that these are genuine. If they are not genuine (not a chance), I will refund your payment.
Thanks,
Leon