Your best bet for getting that M1 vibe without spending money is to explore high-quality and sample libraries. These might not have the Korg name, but many of them capture the same spirit and sound.
This article explores the landscape of capturing the M1 sound, highlighting the official route, top-tier free alternatives, and how to get the most out of them. The Official Route: Is the Korg M1 Plugin Ever Truly Free?
SQ8L produces a wonderfully gritty, aliased, and "digital" sound that perfectly complements the M1's character. Many producers use it as a free alternative for similar string and pad sounds. It's an older plugin, so you may need a 32-bit bridge to run it in a modern 64-bit DAW, but its unique sound is worth the effort. It's a fantastic tool for lofi, synthwave, and any genre that benefits from a bit of vintage digital grime.
When downloading free plugins, make sure to always follow best practices to ensure your computer's safety: