I own one Proto from Raiders of the Lost Ark. I buy it from an Atari Age User for some years as he sold his collection. He dump the Prototype and some Bytes were different. But not the gameplay itself.
What me wonder, it has not work on my Atari 2600 VCS Jr. PAL. But on my Atari 7800 it work without problems.
And I saw one sold on eBay later. The price was not high, but I have not buy it, because one is enough.