Treasure
You can read the Tome of Trade and Goods for prices on many treasures, such as wines and gemstones. As an adventurer, you may want to sell other items you come across. Here's a basic outline of what some objects are worth.
Old coins - About ten times the weight value. (An old Masallan gold coin roughly the same size as an Aranorian coin would be valued at fifty silver.) Such coins must be sold to a collector, and some will be more valuable, some less.
Weapons - Used weapons sell for about half the value of new, if they are in good shape.
Horses - These can be difficult to sell, as most people like to know the history of a steed. You can expect to get about half the regular selling value unless you can make the buyer believe that you know the horse's origins. It's easier to sell an 'acquired' horse to rural folks, but you'll get a much lower price.
Ships - Ships are usually gained from pirates - if you obtain them illegitimately, you will likely be put into a dungeon rather than get any gold. In any case, it's risky to sell them unless you have legitimate title papers on them. A ship, in good condition, will sell for about 75% of what a new one would sell for. Ships hold their value well, because a ship that's been at sea is considered proven and well-built.
Ancient Weapons and Artifacts - Old cultures left behind some curious items. If you hold out and sell to a collector or knowledgeable sage or museum, you can make a small fortune on some of them. If you sell to someone who doesn't understand their value, you probably won't get much.
Chalices, Crowns, Dinner Sets, etc. - Such treasures are often the loot of pirates or bandits. You can get standard prices (consider the materials, any gems, and workmanship), or, if you take the time, you can find a collector that might know that the crown you have was stolen from King So-and-so a hundred years past. Such antiques can be quite valuable.
Chests - Don't forget that the chest often used to contain treasure is a valuable commodity. Large ones, if well made, can cost two to three hundred silver.
Armor - Armor quickly loses its value if it is damaged in combat. If someone in armor has died, that armor is probably pretty far gone. But well-worn armor, only slightly damaged (say with a few arrow holes and a good few dents) can be sold for about half the price of a new set.
Treasure Maps - Adventurers are fond of recording their findings for future reference. Such maps don't sell for much, because it is assumed that most (but not all!) lead to treasures that have already been plundered. You can expect to get about eight or ten silver. It's also a known fact that many people just fabricate them in order to sell them. Still, there can be a real map hidden among many false ones. . .