I believe some of Microsoft's Ergonomic keyboards are highly regarded. I didn't try any of them. Not mechanical but I hear good things. Some of them seem to have a similar tilt to mine. Its not adjustable though and the ergodox folks say you should adjust regularly (I really don't though and I imagine most people don't).
The other big difference is that while the keyboard is split, it is still one piece whereas mine is actually split.
And finally, the ergodox-ez is ortholinear, so instead of key rows that are staggered, the rows of keys are mostly straight vertically, which is supposedly more natural.
At $40ish dollars, it might be worth trying one of the microsoft options.
My keyboard could have been purchased for about $300 without backlighting. It comes with a bunch of different options for the switch, I just swapped mine out (the sockets are hot-swappable so no soldering). I paid more for backlighting because its also got up to 32 programmable layers and you can assign a different color so you know what layer you're on.
There are some slightly cheaper mechanical options. There's a recommendation threat / question thread in /r/mechanicalkeyboards on alternating days where people might be able to help you find something cheaper. I don't know everything so I might be missing a great option for you that doesn't cost a fortune.
One last note, they are not much harder to produce, its just that no one is doing it at scale yet. They are still trying to find the perfect design. Ergodox is one version, there are lots of other split keyboards like iris, artreus62, etc. I think the ergodox is pretty good, but people with small hands might not be able to hit all of the buttons. There are 6 buttons per thumb. Honestly, if I try to use any but the bottom 3 per thumb I have to move my hands significantly, but I assign those to stuff I don't do often. There are other people making smaller keysets, or changing the position/layout to optimize for their use case. If anything ever definitively catches on we might see a mass produced version.
I use split keyboards, and for me I can't go back.
I'm able to reposition them so that I sit up straight and no longer have my wrists cocked at a weird angle. The ability to move them throughout the day means I can change where each half is and how angled they are depending on how i'm sitting (leaning back i'll move them more parallel, sitting forward i'll angle them more "outward", etc...) I also "tent" my split keyboards, so they are at like a 15 degree angle with the inside being the "tallest".
That alone have stopped the carpel tunnel pain I was starting to get while using "traditional keyboards".
But aside from that, the crazier "custom built" keyboards tend to run firmware that allows pretty insane customization to the keyboards which I genuinely can't see myself ever going back. Things like being able to make a dedicated key to commit my work in my editor, what I call "physical bookmarks" which are keybindings that will open websites or apps on my PC, and being able to move around the keys and add layers for various things (my left-alt key acts as left-alt when held down, but presses escape when tapped).
It does come with it's drawbacks though. I have a hard time transitioning back to a normal qwerty keyboard now, and that means I take my split keyboard with me when I travel if I'm expecting to use the laptop significantly. It's not that I can't, but that my muscle memory is really ingrained now and I end up making a lot of mistakes.
$30 is going to be really hard to find a split keyboard for, but if you are willing to get your hands dirty and do some soldering and flashing of components, you can pickup the parts for a "DIY" keyboard kit for probably around $100 if you do your homework. Something like [1] is about $20 for the PCBs and diodes, $20 for the mounting plates, and then you'd need to find some cheap-er switches and keycaps as well as 2 ~$9 controller chips. It's not off-the-shelf for that cheap, but it's doable.
Does it work?
On a side note, I wish I could buy a split keyboard for $30. Are they much harder to produce?