The black missing variety of Scott #2281 is listed in the Scott Specialized Catalog with two varieties:
2281b = Black (engr.) omitted w/MNH Catalog Value of $50
2281c = Black (litho.) omitted w/MNH Catalog Value of $450
As the
ebay seller noted, the varieties shown in the previous scans from the
ebay listings are Scott 2281b.
With
ebay bidding now at $28 for the item, I'm not so sure it may be a good deal, as that is 56% of catalog value, which seems quite high on the resale level. Of course, it is an "error" and that must be considered, but while the item may be "scarce", it is by no means "rare", as there are numerous listings shown on the internet either for sale or having been sold at auction, ranging in price from $10 to $100+. There are also pairs, strips of 5 or 7 and even used varieties shown on-cover. Understandably, the higher end costs are typically for examples accompanied by a expertizing certificate.