A rare Macintosh 128K prototype is currently up for auction on eBay. The seller claims that this is the only Macintosh 128K with a 5.25 inch floppy disk drive.
Apple planned to use its proprietary Twiggy disk format in the Macintosh 128K. But due to production issues, it switched to the 400k Sony 3.5-inch floppy drive in the last 2 or 3 months before the scheduled release on 24 Jan 1984.
The computer and keyboard are dated 1982-83. It can still power on but will require a Mac software on a Twiggy disk to boot up. Sadly, the seller does not have any Macintosh software on Twiggy disk to boot up the system.
It is still unknown how the seller managed to get his hands on a Macintosh 128K prototype with Twiggy drive.
If you are interested, the Macintosh 128K with Twiggy drive is on eBay with starting bid of US$99,995. It’s kinda expensive but if you are a vintage Apple collector, I’m sure you will want to get your hands on this rare prototype.