For those not in the know, the Commodore 65 -- also known as the C65 or C64DX -- is a prototype system that was produced by Commodore in the 1990 to 1991 time frame. It's said that no more than 200 units of the machine were built, making it a very rare gem indeed. In fact, a system that went up for sale back in 2015 fetched a whopping $23,000, which means that the current $28,000 offer isn’t too far off the mark.
The Commodore 65 was powered by a CSG 4510 processor with a clock speed of 3.54MHz and a VIC-III graphics chip that was capable of outputting at up to 1280x400 from a palette of 4096 colors. 128KB of memory was installed, but it could be expanded to 8MB. Other features of the machine include a 1565 external drive port, serial port, C65 expansion port, and two joystick ports. On the bottom of the device is another port for expanding the memory.
The machine was supposed to be backwards compatible with the venerable Commodore 64 and was intended to extend the company's fortunes well into the 1990s. However, Commodore soon filed for bankruptcy, which meant that those hopes were dashed. After Commodore was liquidated, these C65 prototypes finally saw the light of day for the first time and became highly sought-after pieces of Commodore folk lore.
For more information on the Commodore 64, you can visit this [ancient looking] site for some insightful thoughts on its history and development (along with plenty of pictures).
If $28,000 is simply too much money for you part with for a nearly 3-decade-old computer (and that is likely true for 99.9% of our readers), you may want to take a look at the open source MEGA65 project.