While the NTSC Stadium Events currently on eBay is arguable more rare (and definitely more expensive), this 3rd party Tengen AC Adaptor is quite a unique item in its own right. For a lot of collectors, (myself included) this is the first time this cord has ever been seen.
Sealed though, but not cheap.
Take a glacne at the questions on the Stadium Events if you if have a chance.
Will you sell this for $1200? No.
Will you sell this for $1300? No
Will you sell this for $1400? No.