If the Atari 7800 DeLorean is authentic, it's the rarest of anything in the realm of Atari 7800 collecting. A DeLorean owner in Michigan sold one of two prototypes to a person selling his on eBay. It was not converted by Atari, from what is known. It was not going to be mass produced or for sale nationwide, etc. Only 50 were to be made for one DeLorean dealer. Two are known to possibly exist.
The Atari 7800 DeLorean case is metal-colored plastic, but the unit comes with actual sheet metal overlays. The metal-colored plastic may have been the original plan, but the designers didn't like the look and were experimenting with actual metal...

People say that an Atari 7800 or 2600 Light Gun doesn't exist. However, there was an Atari 7800 Light Gun seen at Video Game Trade Shows... but it looked like the XE gun spray-painted red with slightly different trim. You are expected to use a Best Electronics or Atari XE Light Gun for 2600 and 7800 Light Gun Games. The red light gun depicted on the box for the Atari XE Light gun was the prototype called the Atari G1 Light Gun. If anyone has one of these, I would love to see it!

The originally released Atari 7800 system had a keyboard port, but a keyboad was never released for the 7800. One with a keyboard port may become more collectible than others... though there is a clear cased 7800 prototype system out there, somewhere, that would be more collectible.

7800 PAL, or European, games do not operate on the American 7800 system. Sentinel was only released in Europe and exhists as a NTSC, or American, 7800 prototype. It can be purchased at a fair price as a 2600 NTSC game. Some people have modified the PAL version cartridges for play on NTSC Systems. Klax has also become available to the 7800 System from ResQsoft.

What makes the 7800 prototype scene unique is a Digital Signature Key check in normal NTSC (US & Canada). The prototypes' developer did them on develper systems without the digital signature check (like PAL machines; the Digital Signature stuff couldn't be exported due to crypto laws). When one of those prototypes was put in a normal US 7800, it would just come up with a blank screen! When a developer was finished with a game, they sent it to Atari, who generated the 960-bit digital signature key that the developer then put into the cart so it would work on regular 7800's. American "Klax" and "Sentinel" are known to have the Digital Signature. Other Prototypes may exist, but when people go to check them on a normal 7800, they look like dead carts. You need to check them out on a modified 7800.

For a Pal 7800 System, Best Electronics has a conversion kit (cut a trace or two, change the ROM to one with Asteriods built-in, no Digital Signature check).

Best Electronics has a converter that lets you play with a Jaguar Controller on your 2600 / 7800 / 8-bit / ST / TT Systems. It's advertised as working with OVER half the games, but only works well with half of the Atari 7800 library, as noted above.