As a reference I'm coming from the perspective of a musician who uses IEMs on stage for live performances.

My custom molded pair are from 64 Audio, have 5 drivers in each earbud, but they cost over $1000. I absolutely LOVE them. My universal fit IEMs are from Westone (the UM Pro 20), and have dual drivers. They cost around $299. Those sound great as well.

On the lower end, some of the musicians I work with use Behringer IEMs which are essentially clones of much more expensive models from Westone or Shure.

In my experience, When it comes to IEMs the biggest factor isn't the number of drivers or frequency charts or whatever, but is how well they fit in your ear and how durable they are. That's the advantage of custom fitted IEMs. To that point a huge upgrade for any earbuds or IEMs is to get foam tips instead of the silicone tips that are typically included.

From a quick search online, you can get the Behringer SD251-CL for $35 which is a crazy deal for professional level IEMs. Those will likely be much more durable than the random Amazon IEMs, and in the same price range. (When I talk about durability - it's the cable and the connections at the end of the cable that are likely to break down over time.)

Here's a link (Sweetwater is like Amazon for musicians and sound engineers):

https://www.sweetwater.com/store/detail/SD251CL--behringer-behringer-sd251-cl-studio-monitoring-earphones-clear?mrkgadid=3344197272&mrkgcl=28&mrkgen=gpla&mrkgbflag=0&mrkgcat=livesound&lighting&acctid=21700000001645388&dskeywordid=92700046938655795&lid=92700046938655795&ds_s_kwgid=58700005285225297&ds_s_inventory_feed_id=97700000007215323&dsproductgroupid=779865827999&product_id=SD251CL&prodctry=US&prodlang=en&channel=online&storeid=&device=c&network=g&matchtype=&adpos=largenumber&locationid=9016919&creative=360738227933&targetid=aud-297527862170:pla-779865827999&campaignid=2055912419&awsearchcpc=1&gclid=Cj0KCQiAubmPBhCyARIsAJWNpiPOYnV1XmTuXcloitMR8yKT1iepF58SqB5GjkJ1u50PYrIL-CJwWwgaArmNEALw_wcB&gclsrc=aw.ds