After some requests I've been able to get a deal on these previously popular Xiaomi Bluetooth temperature humidity sensors in a pack of 3.
These monitors will display the current temperature/humidity and can be linked with other Xiaomi smart home products via the Mi Home app. It also has a "baby monitor" mode where it will send you an alert through the Mi Home app when the temperature and humidity go too high or too low.
For those who are into tinkering there is a custom firmware project for this too.
- Under "Ship From, Version, Memory, Color" select "3PCS"
- Apply the coupon Thermomeclear at checkout
Free shipping included, AU only and limited to 500pcs.
I read that as thermonuclear