Weaponcraft

I'm looking to start up a business in your world. What product is in the greatest demand? Where should I set up?
Mercenary, set yourself up in any major trade settlement, you will literally have a stable flow of work escorting caravans through the wild lands separating the various cities, towns, and villages. The work is stable, and plentiful and the pay is usually quite excellent since those of a Mercenary bent are rather rare, most folks never leaving the safe zones around their home settlements. 
If you are of a less martial mindset then I would suggest taking up the production of Weapons and Armor for the local townsfolk, guardsmen, and Mercenary companies. Weapons of reasonable quality are always in demand, almost every citizen is taught to use at least one form of common weapon. Crossbow and polearm being the most common preferences among the farmers and tradesmen. Bows, Javelins, and Spears are commonly needed by the local huntsmen. Spears, Swords, Bows, and Crossbows all being commonly used by the City Watch present in every town. Thusly you will find a regular supply of customers willing to pay handsomely for a well made weapon. This saying nothing of the profitability of custom orders from the few nobles, wealthy merchants, mercenary captains, and few other wealthy individuals living in and around any reasonably sized settlement.
That said, magic users of all kinds are going to find they need little more than to exist in order to have a regular income stream. This world lacks the prejudices against magic users rife in most worlds, here "Magician" and "Healer Cleric" are common job titles. Even Warlocks, Witches, Druids, and half-casters can find themselves flush with a hefty regular income, if they are willing to live in and put their magic to the improvement of the settlement.
On the other hand persons willing to explore and help in the claiming of wild lands adjacent to the settlement will also find themselves with a surplus of high paying employers. In this role Druids, Rangers, Hunters, and Shamans find themselves particularly sought after, due to their connection to and skill dealing with the natural environment.

Item type

Trade/Manufactured good