I wrote a small comparison between
BLON BL-03 and Final E3000 as it seemed to be of interest to a number of people. BL-03 goes near $40 with the near mandatory cable+tip change, whereas E3000 can be found for $50 or slightly less. E3000 also has a remote-version in E3000C which costs $10 more.
Build: E3000 and BL-03 both are decently built in a sense with metal housings and mostly well put together chambers, though E3000 has better overall finish IMO. The big difference is the detachable vs fixed cable. For many the fixed cable is the biggest worry about E3000. Frankly, I've been using mine while commuting and just coiling it inside the jeans pocket for the most part for almost 6+ months and till now - zero issues. Either way, it's one thing you can be concerned about and it's natural. However, buying from an authorized seller will at least give peace of mind for a year (Final is great at customer support) so there's that.
Accessories: E3000 has miles better tips while everything on BL-03 is kind of horrible.
Comfort: E3000 is far more comfortable and lightweight and just disappears inside the ears unlike the BL-03 which can be a constant fight.
Overall signature: E3000 is mildly V-shaped with a warm-ish bass and slightly toned down treble (but it's not dark sounding IMO). BL-03 is upper-mid and mid-bass forward and the treble takes the back seat again.
Bass: BL-03 has more volume of bass and also more sub-bass. E3000 lacks the sub-bass extension but the mid-bass punch has more impact. The bass decay is a bit slow post 60Hz on the E3000 and this is their biggest "problem" IMO. Nonetheless, neither are bass light and can deal with most bass heavy genres but you won't get the skull-shaking rumble from either. I personally find the E3000 to have slightly more textured bass. BL-03 has more extension, but the mid-bass can become boomy on some tracks. No such issues on E3000 for me.
Conclusion: Tie.
Mids: BL-03 is upper-mids forward and while female vocals sound great on BL-03 the male vocals do lack some fullness. E3000 is the opposite: fantastic male vocals and female vocals are just balanced in line. Neither overshadows another. The secret sauce of the E3000 midrange is the instrument separation. A bit of a footnote: Final tuned the E3000 to sound similar to their flagship D8000 headphone (which is one of the most expensive and awesome headphones I've heard) and really the instrument separation is pretty much best-in-class. No, it won't beat the $130 E4000 overall but really for such a low price I've never heard such instrument separation.
BL-03 has their signature "analogue" midrange and E3000 is a bit "cooler" in comparison. It's mostly the lack of mid-bass bleed that makes the E3000 midrange sound ethereal in comparison. String instruments also sound better on E3000 due to their ethereal, spacious nature.
Conclusion: E3000 (for my tastes) but BL-03 is very good as well.
Treble: E3000 treble has more details than the BL-03 and extends better. Overall detail retrieval is also better on E3000.
Soundstage: E3000 is an open-back (semi-closed?) IEM so no wonder that it wipes the floor with the BLON in soundstage department. Soundstage width, height, depth - all are far superior in E3000.
Imaging: E3000 has more accurate imaging and would be class leading in this price segment if not for Dunu Titan 1.
Amplification: E3000 needs more power and usually sounds better on a better Amp rather than just straight outta mobile phones or cheap dongles. Do note that Apple dongle sounded really good and is a fantastic option in a budget for E3000.
So yes, in conclusion, from my perspective E3000 is a better buy and true upgrade over the BL-03. Do note that they need a few days of getting used to because the signature is not aggressive/in-your-face and lacks the immediate surge of details you get from most hybrid stuff. If you get them, just listen to them for a couple days and then go back to other IEMs, that way it's easier to appreciate the mature tuning of the E3000.