I use a KME, same principle of operation. Yeah it was pricy but so were my knives. Had it probably 15 years and it has definitely paid for itself in knives getting sharpened instead of needing replaced. I also consider how easily a blade design will sharpen when making a purchase.
Someone dropped one of my fresh sharpened kitchen knives and it completely severed a tendon in their foot. The surgeon said he could tell the knife was incredibly sharp by how clean the cut was and it made his job very easy to have such a clean cut. Still proud of that years later.