Contents
Comparing Seller and Buyer
Perform some sort of Charisma test between the buyer and the seller. Record the difference between the level of test the buyer and seller pass. This is the Level Difference (ld). If the seller performs better than the buyer then ld should be positive otherwise it should be negative.
E.g. buyer and seller roll versus Charisma. One level is every five whole points the test is passed or failed by.
Example: Buyer and seller roll versus Charisma. Buyer has Charisma 14 and rolls a 16, a failure but not by much. Seller rolls a 5 thus rolling under his Charisma of 11 by six points or which is one full level. Hence ld = 1-0 = 1.
The level difference is then Modified. The modifier should be zero for standard equipment under standard conditions, i.e. ld should be left as it is. Typical modifiers include +1 or +2 for salesmen encountered under unusual circumstances, + or - 1/2 for items for items of particularly fine or shoddy quality etc. and also the Scarcity Modifier.
Once the final level difference has been arrived at, the Cost Scale Factor (csf) can be calculated. This is the factor by which the base price should be multiplied to produce the final price under varying circumstances.
csf equals either A: (2-ld)/2x(1-ld) or B: 1/(1-ld) if ld
<= 0
or ld+1 if ld > 0
If that looks too complicated, here is a table:
|
ld : |
10 |
9 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
-1 |
-2 |
-3 |
-4 |
-5 |
-6 |
-7 |
-8 |
-9 |
-10 |
|
csf A : |
|
|
|
|
|
|
|
|
|
|
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
|
csf B : |
|
|
|
|
|
|
|
|
|
|
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
As you can see, csf A and B are both 1 for a level difference of zero and csf A gets closer and closer to 1/2 as the ld gets lower whereas csf B approaches zero. I personally use csf B for rent and A everywhere else.
If you wish to make your players bargain you can calculate a List Price:
List price = (Final Price or Base Price whichever is greater)x 1+
| 2D6-2 |
| 20 |
Scarcity Modifiers
-1 Abundant. Easily obtained even in small villages. E.g., food, packs, torches, animals, primitive weaponry.
0 Common. Easily obtained in towns and cities. E.g., all standard equipment including weapons and armour.
+1 Available. Possible to find a place that has what you are looking for for sale. E.g., Potions, low-level scrolls, +1 armour and weapons.
+2 Uncommon. You may be able to find a place where you can order one. E.g., rings, rods, staffs, wands, medium level scrolls, +2 armour and weapons.
+3 Rare. This type of item is only found in treasure hoards, not necessarily the one you were after. E.g., Miscellaneous magic, +3 armour and weapons.
+4 Very Rare. This type of item is found in treasure hoards about as often as specific items of the previous type, i.e.. not often. Examples include powerful miscellaneous magic e.g. Hand or Eye Of Vecna, Apparatus of Kwalish etc., +4 or +5 magic weapons and armour.
+5 Unique. These items are usually only found as the main object of hard adventures. E.g. Artefacts, relics, unique scrolls etc.
Nb. Most fantasy adventures take place at a Gurps tech level of about 3 (medieval). However if your society were based on magic instead of technology then tech levels may be based on the society's ability to formulate spells and craft items. In that case the magical equivalent of the tech level in such a society is reasonably approximated by the scarcity modifier above plus 3 i.e.. normal medieval items are magical tech level 3 and artefacts would be level 8; better than we can do with present day actual technology.
Creating Stock Lists
An alternative way of assigning scarcity modifiers is, using a scientific calculator, find the log of the XP value of the item and subtract 1, taking cursed items to have an XP value of 1. This gives cursed items a SM of -1 (not so much common as a drag on the market), 100 XP items a SM of 1, 1000 XP items a SM of 2 etc.
Using this method or the previous one it is possible to generate stock lists for NPC merchants. It is only really worthwhile doing this for magical items as normal items never usually have an SM of greater than 0 so any adequately equipped supplier can probably get hold of them.
The probability of a merchant being able to supply particular equipment is dependent on his/her level. One way to generate a stock list would be to calculate the SM of every item and to calculate the quantity of that item the merchant would be likely to have in stock by comparing it to the seller's level, for example:
Quantity=1d6x
- SM
For magical items, however, it is more useful to be able to calculate their quantity directly from their XP value as listed in the DMG. To this end evaluate (again, using a scientific calculator) inv. log(level/5). This value can be compared with the listed XP values:
If it is less than the XP value then they don't have any.
If it is between the XP value and 10xXP value then they can get one in d8-1 days.
If it is between 10xXP and 100xXP then they have 1d6 of them in stock.
If it is between 100xXP and 1000xXP then they have 2d6 of them in stock... and so on.