| I do consignments, and if it were me I would have called you prior to the trade situation. That way you could have made the decision on whether or not to wait on the trade-in selling, or waiting longer to get a sale that would be 100% cash.
The guy might have thought he was doing you a favor by moving the item as quick as possible by taking a trade-in that may sell faster.
I tend to treat consignments as different from my inventory, since money didn't come out of my pocket for it. From an accounting perspective, it's much easier that way. Using the entire amount of a consignment for financial obligations, is a tricky endeavor that I wouldn't want to tread. The profit from it is mine to use as I wish, but the rest belongs to the customer. I treat consignment as a service, not inventory. The profit is the cost of my service.
As far as what it sold for, your knowledge of it depends on the consignment agreement. If it's for a percentage of the sale, then it is your right to know what it sold for. But, if you told the guy the minimum amount you wish to get, and anything above that is the dealers, then the final sale price is irrelevant. | 
