NPC Vendors can be found in various shops in all cities. Vendors provide three services; Selling goods, buying goods and training skills.
If you are a [citizen] of a town you will be able to purchase items in your town for a lower price than other towns.
Generally vendors carry 20 of each item they stock.
A vendor will restock with double his previous supply if he is sold out. If the vendor has not sold out a particular item, the supply will halve at the time of restock. Mages and alchemists restock every 1 hour (it is also good to know that healers and provisioners also sell ginseng and garlic), shipwrights restock every 24 hours.
Knowing this, it is fairly easy to get a lot of reagents even from even only a few vendors. All you need to do is take your time to make sure the vendors get up to a decent number.
Vendors will buy items from you, but you can only sell items that the vendor itself carries. So a cobbler will buy shoes, and a armorer will buy armor.
Vendors have a limited about of gold available to purchase items, so if they aren't able to purchase all your goods, try coming back later.
Different vendors will be able to train you in different skills. Their training is limited and they will not be able to train you above 30 in a given skill.
To receive training, click on the vendor and select the skill from the context menu that appears. The vendor will tell you the amount it will cost to train. You can then drag and drop that amount of gold onto the vendor and your skill will raise. The sill you are training must be set to gain (turned up) and if you are at your skill cap you must have a skill set to decrease (turned down).
You can give the vendor less than what he asked for, but you will receive less training.
- Note: Since you cannot drag your characters starting gold you cannot use it to train a skill.