I think custom prescriptions for the xreal air 1 are around $80: https://vroptician.com/prescription-lens-inserts/nreal-air

Which I could see that being a deal breaker, but maybe it's lower than you thought

With import tax to the EU, yeah, it's a deal breaker. Even from the UK. Also, that site only has lenses for the first gen, and above -10 there's a surcharge of EUR 70.

I pay more for eyeglasses than for a Quest 3, so... I don't want to double that.

There is no import tax for the UK. I paid £60 in total for my lenses from official partner HONSVR. There are cheaper options on AliExpress.

No, but there is from the UK to the EU, thanks to Brexit.

HONSVR is a Chinese company shipping from China. If they are attracting Brexit charges they are doing something wrong. I guess it might be different for XREAL if they use UK warehouses.

I know what you mean. I can't help but wonder what it would take to make a pair of these. The hardware requirements for low-vision users would be lower, as we wouldn't need things like ultra high definition displays.

It's not too difficult to actually assemble - you just need some displays, a display driver, and the optics - but getting optics fabricated to meet your requirements might be challenging.

It is too difficult to assemble precisely for that reason.

The assembly is easy: the part sourcing less so ;-)

I had soemthing like -9.50, but had LASIK, and now I can't focus on anything less than eight or so inches away. I have never tried AR glasses or a VR headset, would they work?

They should work, because they are at infinity in your eyes' perspective.

Virtue One's prescription insert is $100.

Disclaimer: the following is bad medical advice, do not follow.

VR/AR/MR headsets aren't precisely focused at infinity, it's usually 10ft or so. They also have lower resolution than human eyes(~60 px/deg or 1MOA) while at it. This combined means you don't need full correction, I personally use -3 for both eyes, and it seem to work for me in VR.

YMMV.