Buying firewood is a task exceeded only by cutting it yourself. Obviously, it is best to buy it out of season. First, the lack of demand brings the price down. Second, it allows the wood at least fifteen minutes to dry. Okay, it would be better to let wood "season," that is, set for a season to dry.
A cord of wood is 128 cubic feet. No more, no less. That means a carefully stacked (within reason) pile of firewood should measure 4'x4'x8', 2'x8'x8' or some other group of dimensions that,when multiplied, equal 128 cubic feet. It doesn't matter, as long as the numbers multiplied equal 128 cubic feet. If your wood has been cut to eighteen inches, you'll have to fire up the calculator and use a 1.5', or foot and a half calculation to figure the quantity (e.g, the pile would be about 3'x5x8 (120 cu ft)). Finally, keep in mind, it is not loose stacked. I had one jerk claim cords were only measured that way. Based on the two hundred cords he had for sale, that meant he would realize what was more than a years income for many in additional profits by shorting people that way.
The law in Washington doesn't tolerate the games many selling firewood play. You can report them and things can go down hill for them from there. In fact, the law here in the Northwest is very specific in addressing fire wood sales -There can be no "short cords" and other games. Other states have laws regarding the sale of wood too. You may want to check your state codes on line to learn what your rights are. People caught breaking the law (e.g., stealing from you and your family, tend to be easier to negotiate with). And don't hesitate to report jerks who pass green wood and such.
To protect yourself, always insist on a receipt. The receipt should clearly show the seller's name, address and phone. You should also note the delivery truck's plate number on the receipt. Finally, the receipt should clearly state the terms of the agreement, including the type of wood, the cut lengths, if important, the quantity and the age of the wood (e.g., is it green or seasoned (not to be confused with wet wood)). Even if your state doesn't have strong laws about the sale of cord wood, it does have strong contract laws and the transaction of buying firewood is a contract transaction.