A cord of wood is 4 feet high, 4 feet wide, and 8 feet long, stacked tightly. That is 128 cubic feet. A typical full size pickup, bed level, will hold about 1/2 a cord. Be cautious about what you buy, because it is easy to stack a cord so that it contains as much as ten percent less when restacked.
There is also a measurement called a face cord, that is 4 feet high, 8 feet long, and some variable width. Obviously, not a full cord. Buying wood by weight is also somewhat dubious because moisture content and wood density varies greatly depending on the species of tree and amount of seasoning (drying) given the wood.
Costs vary dramatically depending on your location. There's a guy selling it on eBay for $150 per cord. I find prices range from less than $100 a cord to several hundred dollars. It depends on how close you are to forested areas and how much demand there is in your area from suburban consumers. It might also depend on how cheaply the teenager next door wants to work. Cutting and splitting a cord it is easily one or two days work even if the trees are already down.