Are cheap Amazon treadmills under $300 worth buying?

For walking pads and under-desk use, yes — multiple budget models earn solid verified-purchase reviews and decent specialist-community feedback. For running, specialist treadmill subreddits repeatedly warn that 'alphabet-soup' brands often have weak warranties, undersized decks, and motors that struggle under sustained load. If you plan to run more than a few miles at a time, plan to spend more.