marginal cost
incremental cost
differential cost

Only incremental costs and efforts should be included in the item cost.

The incremental cost for an additional F-22 was estimated at about $138 million.

The estimated total annual incremental cost to the industry is $81.9 million.

The incremental cost of adding three 80860s is £18,000.

All routes could be above incremental cost and the problem would still exist.

But the incremental cost is relatively small to raise the benefit to say, $150,000, from $100,000.

The analysis shows that the incremental costs to the industry as a whole are estimated to be $111 million annually.

The incremental cost for additional rooms has not yet been announced.

At this point all we can worry about is the incremental cost of selling each additional unit.

If you have a vacation house, the thinking goes, the incremental cost of donating a week is low.