What are the music genres that you usually listen to? And what type of sound signature do you prefer? That will help us advise better.
The KZ AS16 and CCA C16 (8BA each) are quite neutrally tuned and are more suitable for stage monitoring and critical listening.
They may sound a bit boring for normal music listening IMHO. Maybe unless u like classical music.
The latest CHIFI with excellent reviews and are < $40 USD are the TRN V90, KZ ZSX, CCA C12 and BLON BL-03. You can ask or check out this dedicated CHIFI thread:
https://www.head-fi.org/threads/chinese-asian-brand-iem-info-thread.820747/
And since you are gonna use it for public transport, an IEM with good isolation is also important.
Personally, I use the TFZ No. 3 and KZ ZS10 Pro for public transportation daily, these 2 have good isolation. The TFZ No. 3 is a basshead IEM, so it has very heavy subbass and midbass. It is a single DD IEM, so it is good in timbre and bass, but may lose out in details/clarity to some IEMS with multi BA/hybrids.
The KZ ZS10 Pro is a hybrid with V shape sound (boosted treble and bass) and has good clarity/details/instrument separation for the price point of $35 USD. It's successor, the KZ ZSX as
@buke9 advised above has many great reviews and is an improvement over the ZS10 Pro, also < $40 USD.
Yep hope u find the IEM u are looking for. With a budget of $150, you can even get some good midfi CHIFI IEMs, not to mention multiple budget ones.