It looks like they are back in stock mostly and there are various choice.
Also, confirmed cases in our state are surging upward, so it seems like it might be good to have one on hand... no pun intended.

Any advice from those who've purchased one?

I bought this one, but it was only $29 back in March.

I bought based on availability and price. I don't know if it's a good unit or not.

https://www.amazon.com/gp/prod..._title?ie=UTF8&psc=1

Uses a couple of AAA batteries, which we always have around the house.

The unit is designed for someone other than the person being tested to read, so if you're reading you're own you either have to read upside down or bend your finger.

Wow! That one has way more ratings than the one I saw. I'll take a look, thanks!