Recently, I've been looking into switching to a keyboard with an Ortho split layout. I want the cost to be as low as possible in case I end up not liking it. Any kits that would work for this?
US btw, if that matters for availability
Second hand mechanical keyboard from craigslist: $20 or even less if you're lucky
Pro Micro MCU from aliexpress: $5
100 pack of diodes from aliexpress: $1
Assorted lengths of wires: $2
Desolder all the switches you need from the old keyboard and reuse the keycaps. Make a grid to mount the keycaps in by cutting out squares from cardboard and gluing several layers together, and stick the switches in the holes. Handwire everything and connect both sides to the same MCU, which should work as long as you don't have too many rows and columns. Flash the MCU with QMK.
The trick to switchich to ortho layout, or anything else vastly different from what you're used to, is to go all in. If you only use one at home and keep using a "normal" keyboard at work you'll likely never get used to the new layout. For me it took about 1 week until I could write comfortably on split ortho and a couple of more weeks until I would type at my old speed. Now that I'm used to it I have no problems switching between split ortho and traditional keyboards.
That shouldn't be any noticeable change, just slightly more comfortable for your wrists. If you don't like it you can move the halves closer to each other to make it more similar to non-split ortho. IMO the only disadvantage with split is that the keyboard might get a little bit more difficult to transport, if that's something you need to do.
This is almost exactly how I built my first keyboard. Except of course I laser cut a top and bottom plate out of steel and used brass spacers to separate them. Costs a little bit more but I found the donor keyboard in the electronics recycling at work so it was free.