I understand what you say, too much earphones have bassy soundsignature that rumble and go out of control, or the earphones have a bright, analytical soundsignature and forget about roundness of bass impact.
If you search in sub-30$ earphones, there some exceptions, but they are rare and I don't test them all for now. I can say for sure that open back earphones and dual-drivers can have bigger soundstage, in fact, more the earshell go outside you ears more it feel outside your head. I was thinking this type of soundstage was just limited to extremly expensive custom earphones like the Westone ES2 I have but with chinese brands.
From what I read I can say there a BIG hysteria phenomenon about the Easy UE double drivers custom earphones, look like a very well balanced earphones with big soundstage and lot to like, check the link
http://tinyurl.com/zvxpgu5.
Super clean sound is hard to find in sub 50$ but there couple of dual drivers earphones that can do well and with a risk-free price like the KZ ZN1 (big soundstage, punchy bass but not alot of texture and laid back treble) (10$ on sale in Aliexpress), the Rock Zircon (10-15$) (round bass, good sudbass, warm sounding mids, okay highs), DZAT DF-10 (17-25$) ( airy sound, over average soundstage, round bass, beautifull mids, warm and musical presentation), **** F05 (10-15$) (dark neutral sound, good instruments separation), Vsonic VSD1...
Firstly, what type of music you listen to and what is you music source?