Finding solid 4K action cameras under $150 is tough - most name brands like DJI and Insta360 have moved upmarket, so you're looking at older models or lesser-known alternatives. The sweet spot in that price range is usually stuff like the Akaso or Apeman brands, which shoot 4K but honestly the image quality and stabilization won't match GoPro, though they're decent enough for casual vlogging. If you can stretch closer to $200, you might catch a sale on older DJI Osmo Action models, which would be way more reliable. Before buying anything, check the actual video samples on YouTube from real users - don't trust the marketing specs, since budget cameras often oversell their capabilities.