I used to buy distilled water as well. But like you said, it became scarce. I looked into distillation but the cost of the machine and operating cost was prohibitive. So, I cobbled together a very affordable RO system with a sediment filter, a carbon filter, and RO membrane.
I am getting 1 gal in 18 min @ about 14 ppm thru it. Tap is 140 ppm.
I use the filtered water in the coffee maker, ice maker, humidifier, cat’s watering bowl, and in the brewery.
Prior to using the RO filtered water I tried tap water in the humidifier. It wasn’t long before I was blowing white powder and leaving white residue in the machine. I don’t have that issue now.