Count out the M21, it's Bass is good but more like the M6. The M31 will shake your teeth loose, But it is boomy and bloated and smears the rest of the spectrum out. I hate the JVC personally, I fell for all that hype in that tread, most of those IEMS are trash, sorry!!! If you ask me the M21 is the best sounding out of those by far, but you're not going to get the pounding Bass, it's good tho.
All MEE'S M-series are slightly V-shaped so you'll get decent Bass out of any of them really.
For me I think their CW31 Woody is the best IEM they have. I've had or tried all except the 161, Which i'm not going to bother.
For Bass in your range, Maybe the E30 from Soundmagic?, I haven't heard it tho, but it has good reviews.
Another option around $30 is the Vsonic GR99 or GR02 if you can find a sale? For me the GR99 is the best sounding IEM mentioned, it has a lot of Bass but not sub-woofer like, so it really depends on what you're after, music taste, source ect?
I still Say the Vsonic GR99 can't be beat for $27, it sounds better then any of MEE'S offerings, in the M-series...But everyones ears are different....I'm a MEE fan and for budget IEMs their great, Fantastic even.