Aliexpress. Spares are €3-6. Quality differs, so it’s a bit luck of the draw if you get a good one. But for that price I could just order a handful different ones and pick the best.

I printed a cut-off case that doesn’t cover the keyboard attachment part. I just took a random case 3D file for my phone from yeggi.com and cut the bottom part off in the slicer.

On an old phone I used before I printed the attachment big enough to wrap around the case I was using.

I hope you didn’t throw out the priv and key. In working order they are ~€150 each on ebay.