At the current rate, the auction wouldn't bring enough to cover the accumulated tax bills.
The auction brought a total of $7.1 million, a record for a tribal art sale.
Forward auctions can also bring benefits when making business purchases.
Its first auction of space race paraphernalia, in 1999, brought $1.7 million.
The auction brought in $15.3 million, the highest figure ever for a sale of silver.
The auction brought in $307.3 million, about three times the amount the auction's officials had anticipated.
Christie's says the auction may bring a total of $1.5 million.
Now, he says, the auctions have brought sellers out in the open.
The first auction, held last October, brought in a similar amount for 48 cars.
One auction brought a high bid of $21,600 for all 19.