For an inexpensive but useful starter I'd be looking out for a used mini3 or mini2 from someone who has traded up to mini4.
I'd hope to get a 2 under $200 and 3 under $300.You need to be aware they are bound to a user account and the seller has to unbind them via the app.
Despite being tiny they are remarkably capable if you avoid strong winds but up to 25 mph is more or less OK.