I am not a fan of how later D&D editions (particularly 3.X) reduced magic items to a simple commodity. I get that some of the rules about crafting costs and times were a bit subjective before, but I fall into the camp that magic should be magical.
That being said, players will want to find ways to spend their loot and one of the most useful things for an adventurer is better gear. Once the fighter has bought plate mail and silver arrows, his upgrade options in the standard price list are a bit thin on the ground. I sometimes do have the odd item or two for sale in towns. Usually its things like potions or scrolls and other "limited" magics.
The current campaign I am running, the PCs have managed to get through two adventures, both times clearing a fair amount of coin; enough that the PCs that have survived since session one are at or near level 3 (except the elf). The nature of the adventures limited the chance to find items, though. I am thinking of giving them a chance to acquire some magical shinys. The question is how to decide what's available in such situations without being utterly arbitrary.
The idea I am currently playing with is based roughly off of the Treasure Type Tables on X43. The larger the town or city, the better the chance of any magical items for sale. Likewise, certain types of items are more often found than others. A first pass at this for a typical BX fantasy setting (not particularly high or low magic) might look something like:
Small Town or Village: 15% Any 1
Medium-sized Town: 25% Any 2 + 1 potion + 1 scroll
Large Town or Small City: 1d4 scrolls, 30% Any 3 + 1 sword, armor, or weapon
Large Metropolis: 1d4 scrolls, 2d4 potions, 35% Any 4
It's up to the individual DM to decide where a given population in his setting falls on this list. As examples, I would say a town like Threshold in Karameikos would be a medium town, whereas Specularum might be a small city. You might also tweak how you roll based on things like how much trade or traffic a location sees or if adventurers are common there.
In my campaign, the party is currently in a town of 3,000-4,000 people; what I would consider medium-sized in my setting. But, it is also a busy river port that sees a good deal of trade and adventurer types are not uncommon here (a name-level mage has a tower just outside the town walls). Therefore, I have chosen to roll as a large town/small city.
Roll results are as follows:
1d4 Scrolls = 1. The % dice came "00"! Which is a nice treasure map to 5d6 gems and 2 magic items. Buuuut, the party is already following one map and I am trying to generate magical items here. So I re-rolled that and got a Protection from Magic scroll.
% dice for other magic = 30 exactly (!) So 3 items plus 1 arm or armor. I rolled a d3 to see which and got a 3, which is a non-sword weapon.
The percentile rolls for the specific items came up as follows:
- A potion of Giant Control
- +1 Spear
Staff of HealingStaff of Striking (18 charges)
- A MU/Elf spell scroll of 3 spells. This came up as one 4th, one 1st, and one 2nd level spell. I rolled randomly (d12s) and got Charm Monster, Ventriloquism, and Detect Evil.
Now this is a pretty impressive haul, and frankly a lot more magic than I like to be just lying around. If I want to let these results stand, I need to make sure these items aren't too easy to get. Namely, they need to be expensive or require the PCs do something to get them.
The protection scroll isn't limited but pretty nice, so I will peg that at 1000gp.
I decided to roll randomly for what type of giant the potion can control. There are six kinds of giants and I rolled a 4: Fire Giant. This is pretty neat, but of limited usefulness. However, commanding 1d4 fire giants even for only an hour could be pretty epic. Let's say 1000gp
The +1 spear is nice, but is just a bonus to hit and damage. 1000 gp should cover that.
The healing staff is another matter. I will invoke DM fiat and say this is too powerful to be simply bought in town, ready to go. This item allows essentially allows a cleric to cast a Cure Light Wounds once per day on each PC and uses no charges! This sort of thing would be snapped up by one to the temples in town and not readily available to wandering murder hobos. Like with the map, I re-rolled and the result was a Staff of Striking with 18 charges. This is a nice item, but limited by who can use it (clerics) and finite charges. I will judge it roughly equivalent to the spear and set its price at 1000 gp as well.
The spell scroll would be pretty expensive. I have previously established house rules about spell books and scrolls, so using those I can pin its price tag at 3,500gp (7 spell levels total at 500 gp per). Since they are all on one scroll, it's an all or nothing price.
Now, this is a pretty generous haul, but the rolls were with them. The odds favored 2-3 scrolls and that's it. I would also argue that it would be a while (a month or two at least) before this particular town might be "restocked." Over the course of a campaign, I would see this as balancing out. I'm not sure it's the perfect system. I still needed to intervene a little to maintain what I see as a correct balance, but isn't that what DMs are supposed to do?