Did a bit of research on this stuff...
Panasonic HJ50-K: Not quite the well liked HJE50, but I'm not sure if or what the diff is. One person who owned them thought they were thinner sounding and harsher than the EP630, and was not crazy about them. Overall, they get good marks from many.
JVC HA-FX55: JVC's HA-FX33 model (aka "Marshmallows") are considered a budget winner, beating out many costlier models for much less, due to their great tonal balance and other qualities. For example, some consider them to have better bass than the EP630 (which has been criticized as a one note bass), but that they are flawed in their limited detail. I know less about the HA-FX55, except that they have less bass than the Marshmallows, and one person who's listened to both said he would not recommend the FX33 over the FX55. One person compares them to Sennheiser MX400's, saying that they are similar in clarity, with the JVC having stronger bass and the Sennheiser having better mid's, but that the JVC is a better listen. One other person thinks these JVC suck:
http://www.head-fi.org/forums/showth...hlight=ha-fx55
iVoda: I had found a few people on Yahoo and eBay auction sites who bought the iVoda's from this seller, and either left pos. feedback on their SQ (sound quality) or told me they liked them. Don't know any more than that, other than they are CX300 knockoffs made by OVC, which has made buds to measure for better known companies like V-Moda,etc. The CX300 from Sennheiser is considered somewhat better than the EP630 from Creative, but not quite as bassy.
iSony: An unknown to me. They could be decent. They are clones of a Sony model, E51 I believe. The i-Vodas are clones of the Senn CX300. Let's say for the sake of argument both of these clones approach (if not surpass) the sound of their original models. Well.... the CX300 sounds better than the Sony E51 to start off with!
Griffin Earthump: One person thinks they are great for the price... bassy at first, but that loosens up. One other person thinks they were awful, not as good as the HJE50. Another person doesn't think they are awful, he believes they are merely "horrible". One says mids are a bit recessed (another agrees they are muffled), and they are no better than the Apple iPod buds and worse than the EP630's.
Skullcandy Smokin: One person compares them to the JVC HXF55. A few consider them ugly, and one didn't like the sound of them in the store. Another compares it to his JVC HXF33 Marshmallows, saying the Skull's wouldnt stay in his ears, so he took the buds off the Marshmallows, and now the Skulls sound better than the JVC Mallows.
V-Moda: VModa is a good brand name and they are likely not fakes, but I dont know the rep of this model, though I'm sure they must be pretty decent. I have ordered on eBay an OVC bud that is a knockoff of the VModa Vibes, and cheaper than this VModa model. I should be getting it any day now for review.
CX300: I have my doubts that those are true CX300's due to the price and that the box does not say "in ear canal" (it seems from my research, more of the fakes come in the alternative box of "blocks outside noise"). However, true Senn's could have either box, and there's a better chance than not that they aren't fakes, I suppose, but no guarantee here. (Dont assume because they come in the retail box and are being sold in the US they aren't fakes. Just the fact that they're on eBay makes that a great possibility!)
If you want me to pick out what I think are most likelyi true CX300's on eBay, I can, but it'll likely cost more than the ones you found.
If you want clear, crisp sound that doesn't have overwhelming bass, well I wouldn't rule out the Senn MX400's. Even though they are as cheap as your original choice.....