I bought them right off amazon for the place I work. This one is pretty good and affordable. It also depends what you’re using to record video with.... we use these with our iPad setup.
Lavalier Microphone, Omnidirectional Condenser Lavalier MIC for Recording YouTube Interview (Suitable for iPhone/Android/Windows/Camera) https://www.amazon.com/dp/B07SPZPPYQ/ref=cm_sw_r_cp_api_i_k42lEbC50YXRY
Please click these amazon links, you need it, otherwise great videos!
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I use the Rode Smart Lav+ as a backup to my backup video production gear. For the price it's tough to beat and the cable connections seem to be sturdier than others I've tried. If you want you can try a cheap off brand from Amazon but just make sure it has the TRRS connector. Like this one: https://www.amazon.com/Microphone-Omnidirectional-Condenser-Recording-Interview/dp/B07SPZPPYQ
In either case you'll need that lightning adapter. And honestly, maybe buy a couple extra adapters as backup.