A butcher's steel keeps the edge honed. If the edge gets too worn, then a stone or ceramic sharpeners should used. I touch up my knife several times when i clean fish.
That's what you should invest in. A good steel is priceless. More times than not, a few good swipes on a steel and you are good to go. In a pinch you can also use a long philips screwdriver. Steel sharpens steel.
Don't knock a $5 knife. I picked up 2 decomissioned processing knives at a local bait shop in Ludington. They are my go to blades for everything from gills to venison.