The Soundmagic ES18 is better and cheaper than the JVC HA-FX101. The HAFX101 gives artificially boosted mid and upper bass which doesn't sound natural, and it seems deficient in deep bass. I guess this is due to its drivers only being 8.5mm. The Soundmagic ES18 at $12 sounds very musical. It does seem to give a bit of extra bass, but still sounds natural. It has 10mm drivers, so its bass reach isn't as low as the HJE450 or EX210B which have larger drivers.
Other IEMs under $25 that I like are
Panasonic RPHJE450(in white it is under $25)
The HJE450 is my go IEM as it is very comfortable and fits great due to it very ergonomic shape. It has 12.5 mm drivers, so it gives better bass than most IEMs with smaller drivers. It is ported though, so isolation isn't great. The Sony MDR-EX210B has 13.5mm drivers so it is great at giving deep bass. It has a very smooth, slow sound(Sony calls it rich). It doesn't have as much detail as the HJE350, but its bass is more impactful. The HJE355 has less bass than the HJE450 but more detail.
The ES18 for just $12 seems like the best buy.