Ninja Gaiden NES Prototype
Ninja Gaiden, first released in arcades in 1988, and later on NES in 1989 (North America), is known for its innovative use of cutscenes and notorious difficulty. Prototypes of NES games are commonly sold for high prices, and are also highly coveted by those who don't want to own simply retail versions. Often times, a prototype will contain unfinished content, cut content, and edited content. These edits may be censoring of certain text and pixel-violence, or simple color swaps. This prototype of Ninja Gaiden already has 12 bids and is up to $770 USD, so if this is your "holy grail" of NES games/prototypes, you're going to have competition.
I have found some more arcade cabinets for sale, but I wish I knew more about them. I can not ensure that these are reasonably priced, but they are some easily recognized games.
NBA Jam Arcade Cabinet - Local pickup or have a shipping company take it to you
1979 Space Invaders Cabinet - Plays 8 games, has worldwide delivery
Donkey Kong Arcade Cabinet - Has free shipping, but the price seems pretty steep at $2,500 USD
Super Pac-Man Arcade Cabinet - Local pick-up in California, definitely has seen better days but does have bids
Star Wars Trilogy Arcade Sit Down 1 / Star Wars Trilogy Arcade Sit Down 2 - I have found two auctions for the Trilogy Arcade, and they both seem to be in good condition. They are both in the $2,000 USD range, and it seems like they might not be worth that much. One has bidding starting at $1,500 USD and the other is a buy-it-now or best offer at $1,995 USD -- both have a freight shipping option.
On to some other auctions
Exile: Wicked Phenomenon - A hard to find game for TurboGrafx-CD, one sold for only $45 USD last year and this one is up to $150 USD
Signed Gold Legend of Zelda Game Boy Advance SP by Shigeru Miyamoto - This is something I wish I had the money for, as Miyamoto does not sign very many items.
Toys 'R Us Gold Nintendo 64 System In Box - Includes everything to operate, and includes Mario Kart 64