Although the EP630's are said to be so close to the Senn CX300's. I found that they sounded quite different. Its true that they look almost identical minus the logo difference, but the Creative's have a much larger increase in the higher frequencies. (around 4-12khz). It is to the point where i find them quite harsh without any eq adjustments. I find I have to use a completely different eq to get the phones to sound similar. Over all i prefer the sound of the Sennheiser buds.
One thing to note though, is I have had the Senn buds for over a year, and have had issues with wax build up. This may partially account for them having less high frequency response.
For your price range another set of phones to look at would be the Klipsch Image S4's. I haven't had any experience with them myself, but most reviews seem to be pretty positive. I have just ordered them and they should arrive tomorrow. After I've given them some decent burn-in time, I'll hopefully report back.