I wish I had a source for you for black levers. That being said, Polaris ‘sourced’ the levers and their associated parts. They didn’t design them specifically for your bike.
Therefore, they’re very likely a common Japanese bike lever. Just like our gas caps.
I’d find a large aftermarket bike parts store and with your levers in hand, start comparing them to similar model year Japanese bike levers. I suspect you’ll be pleasantly surprised at your options.
Is there a manufacturer name molded into your OEM levers or the mounts? A name like Nisson or Magura? The bottom line is, they’re common. Finding out what else they fit is the trick.