Small version with 2 different filters ~40€, big version with 4 different filters ~80€. All come without any kind of carry case / pouch. A bit expensive and lacking for that price tbh

The 2 pair of IEMs I use by far the most are my Blessing 2: Dusk and the Galaxy Buds 2 Pro (for convenience).

The Cheapino gets quite some love recently :D Saw a couple posts in the last weeks, really cool! I too built a Cheapino for myself and a friend who wanted to try out these ominous "ergo mech keyboards" 😁

Nice case! Basic but functional, pretty good for a first

Wow, really cool :D I'm wondering why you went with a straight line for the thumb keys instead of going for a curve (which so see with a lot of ergo keyboards). Is there any general benefit or is it just more comfortable for your hands?

That's a really interesting case design too! Cool to see that you're taking into account that one might bring it into the office or so and needs a "travel" case as well.

Galaxy Watch 4. I don't like Samsung but I wanted WearOS 3 so yeah...

Cool! I'm happy it actually helped you :)

I also own the Cheapino and made myself a keymap which is fully working. You can have a look at it here. Hooe that helps at least some bit.

Regarding the qmk toolbox: You can take the json file from one of the keymaps in tompis qmk_firmware repository and upload it in qmk toolbox. Then you can have the correct layout and you can configure it to your liking.

One of the cheapest options might be building a cheapino. It should be around 50-70$ all in all. Though it's completely DIY and not the best option for beginners.
You'd have to order the PCBs and all the other stuff yourself and build it.
If you don't want to or cannot do that, there are already a lot of good options in the other comments.

EDIT: spelling

Ohhh I didn't even recognize there was a little switch. Really cool! Thank you

That's a really cool build, well done! I'm wondering how you're using the trackball and mouse clicks. Do you use the trackball with your index and middle finger and have left and right mouse click on the thumb keys to press them with the thumb?