I have just recently purchased a pair of EPH-100 on eBay, and mine look identical to the ones on the images 118R3volution posted on Page 253. Very apparent grooves around the housing and light print on the Yamaha logo on the left earbud.
However, unlike you I don't have much previous experience regarding earphones. On the other hand, I have done some research and found out that these are being sold of AliExpress for as low as $39.99, and the Chinese equivalent of it ( http://www.1688.com ) for 125-150 Yuan, or $20-25 USD. The pictures they provide in the packaging look the same as the one I received, but they only provide them OEM, without the package.
Also, I didn't receive 5 pairs of tips in the package. I saw that the legitimate package comes with a little ziplock bag, but mine didn't and only had 4 pairs, one of them in the case.
My eBay seller is based in China and he refused to comment the authenticity of the product, but he said that he is fine with me returning the item for a full refund or even keeping the item for a partial refund, so that's good.
I am heavily inclined on returning these right now. What do you guys think?
How do they sound for you? Do the ear tips included feel unusually soft?