If you think those earphones sound great, you will be totally blown away by the Sennheiser MX580($28). The Sansa earphones are okay, but imo nothing special. I am comparing them to my other earbuds. I think the $8 Sony MDR-E828 sounds a bit better than those Sansa earphones. If you want an in the ear canal earphone(IEM), the $8 JVC Riptidz sounds quite good for the price. This isolates outside noise, so it should only be used when isolation is safe.
The Sennheiser MX580 is orders of magnitude above these other earphones I mentioned. There are of course earphone much better than the MX580, however those are much more expensive.The most I ever spent for an earphone was around $60. That $60 earphone is only slightly better than the MX580.
