Please, anyone, show any proof of a reference to a 128K ED. It dont believe it exists, and have never seen it referenced anywhere. Lots of speculating going on here. This is how some of these Macs come into existence, because people see idle speculation in forums such as this. A lot of it is being passed of with an air of authority as well.
Also, there is no proof of a platinum 512Ke badged as such. I don't believe one ever was. But I am eager for someone to prove me wrong. Either way the Platinum variant would be the rarest of all. Few have been spotted in the wild. The 512Ke itself was one of the most popular Macs, so even though it sold for a brief time, eBay is populated with them, suggesting a significant volume of sales. So, no, not rare. Its European counterpart, the 512K/800 is also somewhat rare.
And yes, it may just be badging, or case variation, but that is what makes them rare. Just like a Star Wars action figure still in its original packaging ... Nothing special about the box, but it can mean the difference of hundreds of dollars in the price.
Again, macman142, if you want pictures and info from owners of some of these things, then DO A SEARCH. Most, if not all of these Macs have been posted by their owners in these Compact Mac forums. Those that aren't are from links that will lead you back to their owners. Also, you might try the M0001 Registry
http://mac128.com/m0001 to see if anyone has posted a rare ED and their contact info. And Scott offered to tell you about his SE 1/20, but you didn't ask any follow ups.