I picked up one of these for my GoPro: https://www.amazon.com/dp/B07FCMKK5X/ref=twister_B07V2PRSXC?_encoding=UTF8&psc=1

$23.77 in the US

https://www.amazon.com/SanDisk-256GB-Extreme-microSD-Adapter/dp/B07FCMKK5X/ref=sr_1_3?keywords=SanDisk%2BExtreme%2B(UHS-1%2BU3%2B%2F%2BV30)%2BA2%2B128GB&qid=1571927085&sr=8-3&th=1

It is on the list of approved cards for both MAX and Hero8

https://gopro.com/help/articles/Block/microSD-Card-Considerations

I'd recommend something like this from Amcrest: https://www.amazon.com/dp/B07WW9XW88

You can get 2 for $70/ea and 2x 128GB U3 A2 MicroSD cards like these for about $20/ea https://www.amazon.com/dp/B07FCMKK5X

For a total of about $180, it'll get you 2x 4MP PTZ indoor cameras with storage. No subscription or cloud required, and you can set them up and review footage either with the web interface or with the app (locally, no cloud).

https://www.amazon.com/SanDisk-128GB-Extreme-microSD-Adapter/dp/B07FCMKK5X/ref=sr_1_3?s=electronics&ie=UTF8&qid=1543190802&sr=1-3&keywords=sandisk%2Bextreme%2Bv30&th=1