If you're doing that many blades then a dedicated sharpener should at least be a consideration. At the very least, I'd see if you could adapt a Magna-Matic grinding wheel to work on your bench grinder (their wheels have a 1-1/4" arbor hole). All grinding wheels feel hard if you bang your knuckles on them, but they're available in a a wide range of hardnesses. Bench grinder wheels are amongst the hardest, which is why they last a long time but also glaze up. The Magna-Matic wheels disintegrate, but as I mentioned earlier I got almost 250 blades out of my last wheel (yeah, I actually keep track), and that included plenty of blades that had never been sharpened and needed a lot of grinding to get back into shape. If I was only doing yearly maintenance sharpening I think I could get well over 500 blades out of a wheel.
Check your local Craigslist and Facebook Marketplace for a used Magna-Matic and maybe you'll find a deal. There's always a lawn care company going out of business that's selling off all their equipment. And if you're curious, here's a video of the Magna-Matic belt grinder in action. He takes a brand new blade with a 30° angle and grinds a 45° angle on part of the edge. He takes off a crapload of material in 12-13 seconds.
