Best lens for recording videos on a phone without spending much

Here the thing is that cheap external lenses almost never pay off - you end up spending money on something that can actually hurt your video quality instead of improving it. If you really want better video, you're better off investing in better lighting and audio (a lavalier mic costs next to nothing and makes a huge difference) because most phones these days already shoot decent video. If you're set on getting a lens, check out brand names like Moment or Sandmarc that run around 50-80 bucks, but honestly with that budget you'd get way more out of a ring light or tripod.