https://suzyquilts.com/worlds-best-seam-ripper/You can pay about $40 for the fancy-schmancy brass one (or a stainless steel version - you're paying for the weight and solidity of metal vs. plastic), to about $5 for the Tulip ones ($11-$12 for a set of 3), and can get the cheapie ones in bulk (ergonomic, no less!) for about $1 each for a half dozen.

Edit opinion - Your time is valuable, and you might have a heck of time getting the right edge on something so tiny if you try to sharpen it. I'd buy a half dozen for $6 and call it good.