To me the line is drawn on slicers by whether they have a built-in sharpener, quality manual and parts support. To me that means buying an old commercial slicer and reconditioning it. I've been rebuilding machine tools as a hobby since the '80s anyway, how hard can a slicer be?
Anyway, to skip ahead, I bought a Globe 725L off craigslist locally for $200. The guy was a bozo who thought you lubricated everything with vegetable oil (which dries GUMMY) so it was not only pretty marginally working in manual mode only, but completely filthy. But that's a screaming deal for a 12" commercial slicer, so I started working on it. Along the way I bought the carcass of a Globe 825L so I could take it apart and learn how to do it, since there is no service manual in existence for those machines. Anyway, I'm getting close to being done and still haven't spent any more money on the 725L, just a bunch of time. But the autofeed works perfectly now, and the outside of the machine is clean and shiny.
Anyway, I would skip all those little Chinese slicers and simply hunt for a complete (make sure it has all the parts 'cuz replacement parts are *really* expensive) commercial slicer.
In my area there's an automatic Hobart 1712 missing one foot and missing the meat carriage, which the guy has listed for $399 but I'm certain he'd take $200 and maybe a lot less.
Of course, big commercial slicers are, well, big. They weigh like 140 pounds and occupy about the same volume of space as a 19" CRT television from the '80s. Big.