My go-to is the SQ-12 or similar. It can be found from a number of companies on Amazon. Usually can be found for $15-$35. Just took a look, it seems most of them are marketed/listed as "Mini Spy Camera" these days.

Example: https://www.amazon.com/Mini-Camera-1080P-Hidden-Built/dp/B07X1YLC2L/ref=sr_1_9?crid=3R7MXTQ9HE6T&keywords=sq-12+mini+camera&qid=1663684811&sprefix=sq-12+mini+camera%2Caps%2C59&sr=8-9#customerReviews