Not all 4K is equal. The key specs that determine 4K video quality in drones are: sensor size (larger is better), bitrate (higher Mbps = more detail), color profile (D-Log M vs Normal), and stabilization (3-axis mechanical gimbal vs EIS).
The DJI Mini 3 Pro is the best 4K drone under $800: 1/1.3-inch sensor, 4K/60fps, 150 Mbps H.265, 3-axis gimbal, D-Log M. The DJI Air 3 at $1,099 adds a second camera and improves on the Mini 3 Pro at every spec.
Budget drones claiming 4K (Holy Stone, Potensic, Ruko) typically have tiny 1/2.3-inch sensors, 50-60 Mbps bitrate, and no log color — their 4K looks noticeably worse than DJI's 1080p from 2019. The minimum meaningful spend for real 4K quality is $299 for the DJI Mini 2 SE: 4K/30fps at 100 Mbps with a 3-axis gimbal.
Check DJI Mini 3 Pro price on Amazon