There are a few rare NES carts that go for crazy money
The 'world champion' ones like this (which are 3 games - Tetris / Rad Racer / Mario on a timer) there are grey and gold ones depending on where the person placed in the event - they were given out as prizes so there are a very limited number.
A very early Wii Fit type game called Stadium Events which was released and withdrawn almost straight away (then came out under another publisher) - one went for something like 15,000 $ last year
The prices are around the rarity of the games not the quality
e.g. one of the rare and valuable VCS games is called "Chase the chuckwagon" or similar which is a poor pacman clone that was given away free via coupons on tins of dogfood in the US , its the fact there are not 'millions' of them out there which makes it worth more
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Edit -
Stadium events stories :
http://en.wikipedia.org/wiki/Stadium_Eventshttp://kotaku.com/holy-grail-of-rare-vi ... -473730982http://www.destructoid.com/ebay-sealed- ... 5022.phtmlChase the chuckwagon :
http://en.wikipedia.org/wiki/Chase_the_Chuck_WagonNintendo world championship :
http://en.wikipedia.org/wiki/Nintendo_W ... ampionship