Cheap slicers are underpowered and have short slicing strokes. Professional slicers often weigh over 100# and even used they are expensive. I ended up with a $300 wannabe-professional where the silver colored b body is plastic instead of the professionals' cast aluminum. It works for me but the cutting stroke is too short to cut bacon slices off of a full belly. I cut the belly the long way and make half-length slices. They taste the same.
Try FB Marketplace. Used slicers seem to be fairly common there, though personally although I love really good tools, the bulk and weight of the professional models would keep them off my list.