Distant Horizons of Lands Long Forgotten and Tales Untold
Iodi's main exports are steel, horses, pale skin, and mercenaries.
Availability of Goods and Services
The availability of something you're looking for is based primarily off how large of a settlement you're in. The exception is Razgauthen forts and Dwarven settlements.
Villages and Hamlets (~50-700 pop.)
Goods. Staple food and drink appropriate to the region, clothing, potentially tools, potentially lumber or stone. Any weapons and armor at all highly unlikely.
Services. Shoemaker and cobbler, tailor, barber, non-magical healer, a couple bed partners, possibly a tavern and/or stable if you're lucky. Potentially a carpenter and/or mason.
Towns (~1-5k pop.)
Goods. That of villages, plus a selection of the most common weapons and armor. Hard liquor. Animals for purchase. General supplies like rope, tools, traveling/camping gear, etc.
Services. That of villages, plus a mason, carpenter, blacksmith, and leatherworker. A hot-spring bath house/spa. Mercenaries. A tattooist. A couple pubs. Some magical healing. An inn, maybe two if it's a larger town.
Cities (~8-12k pop.)
Goods. That of villages and towns, but a larger selection and from a few/several different suppliers. Potentially a craftsman who works with a special material. If the season's right and you're lucky there might be a trade caravan from another settlement.
Services. That of villages and towns but more skilled and with more variety. An arcane caster or two. One of the magic users in town is probably a necromancer. An alchemist. A feast hall.
Big Cities (~25-100k pop.)
Goods. Anything out of the PHB, plus most of the special materials below. A wide variety of suppliers and skill levels. Multiple caravans from other settlements, even in winter. Maybe a magic item or two if you're lucky, resourceful, and do your homework.
Services. Pretty much every conceivable service. A temple of magical healers, a handful of arcane casters. Someone who can raise the dead.
Goods. That of villages, plus masterwork weapons and armor. Potions. Hard liquor. Potentially horses.
Services. Comparable to towns, plus skilled and eager mercenaries.
Goods. Most everything, if it's a hold on a standard trade route. Wide selection, but not made to order.
Services. None. Outsiders are not typically allowed into a hold. At many large and heavily trafficked holds, large camps form outside.
Occasionally, humans will form towns and forts right on top of a dwarven hold. They seem to think they're the ones getting the better of this arrangement. When visiting these settlements, obviously you have access to the goods and services of both settlements.
Cold Weather Gear
The comfort range for a naked Iodian is 30-90 degrees. Wearing clothes lowers the lower end of this range by 10 degrees. On top of clothes, you may wear light, medium, or heavy winter gear. These encumber the wearer similar to armor of the same category. Light lowers the lower and upper ends of the range by 20 degrees. Medium lowers the lower end by 30 and the upper end by 20. Heavy lowers the lower end by 40 and the upper end by 30. The encumbrances of winter gear and armor stack.
Horses are a prized export of Iodi as they are not native to any other lands. They are however bred and used widely across Calithi, but Iodi is their point of origin. Native bred Iodian horses are still quite valuable as they are more naturally suited for combat.
There are two main varieties of horse in Iodi, the coastal breeds and the midland breeds. The coastal breeds are stockier, stronger, and in general are more suited for labor. Midland breeds in comparison are sleek and faster. All Iodian horses are well suited for battle; they do not spook, do need special training to wear barding, and have no aversion to things underfoot.
All animals in Iodi have a chance to be born with significantly greater intelligence than others of their species. This is called "Ukhanti" and doesn't seem to be hereditary as no one has been able to make it happen reliably. About 1 in 1000 horses are blessed with this gift and when someone discovers this about a particular specimen, it can be sold for more than five thousand gold.
Adamantine. Like many special materials, adamantine is a term that's applied in a lot of places it doesn't necessarily fit. Technically, any particularly durable/hard steel can be called adamantine, but adamantium refers to a specific metal. Adamantine has +1 damage (for weapons), resistance to one type of non-magical weapon damage as appropriate (for armor), an additional level of durability, and costs anywhere from eight to fifteen times as much as normal. True adamantium is extraordinarily rare and is effectively priceless. Adamantium is a naturally oily/slick bluish dark grey metal and is only found deep underground, so deep even dwarves rarely encounter it. It's said to be completely indestructible once forged.
Cold Iron. Even though it's often marketed as "cold iron" to make it sound special, ordinary iron has a number of special properties. Iron weapons get -1 weapon damage, but deal an additional 1d4 fire damage to undead, fey, demons, and warlocks. It usually costs the same as ordinary weapons, but special circumstances can of course change this.
Fireoak. Many but not all tree species in Iodi have developed an interesting adaption to the cold; their sap has a high ethanol content. The wood itself burns for twice as long, and the sap makes excellent fuel. If burnt as wood, or if not distilled properly and just burnt as sap it produces a pink flame and an absurd amount of smoke. Distilled further or not, it makes a suitable alcoholic beverage although undistilled it is incredibly bitter.
Ironwood. Like adamantine, many different woods are called ironwood without being proper ironwood. Any particularly durable hardwood is referred to as ironwood, but actual ironwood is truly as hard as iron. Getting one's hands on proper ironwood is difficult and it is not generally sold in public markets. Druids, centaurs, sylvan elves, and a few other few beings fiercely protect ironwood trees as they apparently have some kind of sacred importance.
Fortress Steel. "Fortress steel" refers to the steel forged by Razgauthen smiths, and it is a form of high quality adamantine. It can generally only be found at Razgauthen fortresses. It has two additional levels of durability instead of one, counts as being silvered, and costs anywhere from ten to fifteen times as much. "Holy steel" is also forged at Razgauthen forts, but is reserved only for the order. This metal has all the same properties of fortress steel but also gives off warmth similar to a small campfire and has a slight greenish tint to it.
Mithril. It's not uncommon for specially worked steel alloys to be sold as mithril or "elven steel" when it's not. These imitations can cost anywhere from twice to ten times as much, depending on how convincing they are. They're often significantly lighter than typical steel, a mirror finish, and are of high quality (+1 damage). Proper mithril actually has no origins with elves despite the common assumption, though ethereal elves do trade with dwarves for the material. It's not as rare as adamantium by a long shot, but it's always custom work and the cost is generally whatever the smith feels like charging (generally by weight). It's actually not much lighter than steel by volume but is hard enough that items can be made much thinner and still hold up to rough use.
Winter Wolf Pelts. Pelts of winter wolf fur and leather are valued as cold weather gear. Winter gear made with these pelts has protection from cold as though it were one level higher (heavy gear also halves the frequency of saves against cold weather), and generally costs an additional 100 gold per protection level.