At the moment, there is a complicated little formula that I'm working with. It's based on a range of predefined elements for the equipment to ensure a level of game balance versus cost, then it rounds things off to the nearest whole number.
I know that there are people who say "point buy systems can never truly be balanced because every character and every player valies things different,y according to their character motivations". That's true, but at least this idea is giving a rough estimate of a good starting point. Things can always be tweaked later, once the system hits the actual players.
The combat system is simple, with weapon intensity adding to user's physical stat to apply damage...while armour resilience adds to half of the physical stat to absorb damage. More damage potential means opponents tend to go down quicker...more absorbtion tends to mean that combatants take longer to go down. Since everything uses a ten sided die, then every increment of weapon strength has a 10% better chance to do something (up to a point). If a target has more ability to resist damage than the attacker has ability to inflict damage, then something interesting only happens on a very exceptional die roll. The lower damage weapons have more chance of being simply ignored by the armour, while the high damage weapons have a better chance of getting through and a more significant level of impact on the victim. For this reason, the low increments of damage have a cost increase that is slower than the higher step increments. (Lvl 1 = 6 pts, Lvl 2 = 6+8= 14 pts, Lvl 3 = 6+8+10 = 24 pts...etc.)
Then we factor in the speed of the weapon, some weapons can be used to rapidly strike at an opponent, and they have a higher cost than those weapons that are slow and unwieldy. This applies to the inherent quickness of the weapon, some warriors may train with a weapon and overcome such a disadvantage. Generally, a striking action takes 3 timing ticks; a fast weapon might reduce that by 1 timing tick and a slow weapon might increase it by 1 timing tick. That means the value of the faster weapon is more because it allows 6 2-tick strikes during a 12 tick cycle...a regular weapon allows 4 3-tick strikes, and the slow weapon allows 3 4-tick strikes. Theoretically, if everything else were equal, the fast weapon is twice as valuable as the slow weapon because it allows twice as many strikes.
Next we consider it's encumbrance grid size on the encumbrance matrix. Bigger items mean that a character has to dedicate a lot more of their limited reserve of space, smaller items are easier to carry, more convenient, and thus more valuable to a character. For this I'm simply applying a factor of "height x width" as per the encumbrance grid. This is a deliberate abstraction, because according to the grid, a charact might be able to carry six "2x1" daggers in the same space that they could carry a single "4x3" metal breastplate. But since this game is based off many of the ideas of the old computer RPGs of the 1980s/90s, it fits with the theme.
Then we apply a special category for the quirky abilities that an object might open up for the character. Swords can be used to parry, two-handed weapons have an extra degree of mass to them and are therefore harder to disarm, shields can vary the locations that they protect...etc. each ability gets a rough point value (1 = not that useful, or not useful that often, 2 = commonly useful, 3 = regularly useful and often makes a significant impact, 4 = awesome ability). Very arbitrary, I know, but it allows these quirky abilities to be factored into the cost.
Then, we look at the traits that an item might possess. Individually, these traits don't actually do anything; but characters have special abilities that interact with traits. Warriors can increase the potential of weapons by mastering certain traits (and thus improve their ability with any weapon possessing such traits), spell effects can more easily manipulate items possessing specific traits. So even though the traits may not have inherent power, they do open up opportunity. More traits means more opportunity, more traits also mean an item is more interesting, and thus more valuable. The weighting on this factor is far lower than most other aspects of cost, because it requires an outside force to open up that potential.
Finally, we consider the sockets on the Item. These are places where the magical crystals known as voidstones can be attached to the item (basically taken from the Diablo II game). Like traits, these sockets have no inherent value and they need to be opened up through character actions in play, but more sockets mean that more voidstones can be added to an item and more mystical benefits can be applied to it.
With all these factors in place, it becomes a case of weighting their value in comparison to one another, then scaling the result to a meaningful level.
Current formulae indicate that a knife is worth 3 coins, a dagger (which is specifically balanced for combat) is worth 5 coins, shortswords are 8, longswords are 12, two-handed swords are 30. That's basically the bladed weapons, then there are blunt things like clubs (5) and staves (4)...so you can see how the forumlae seem to be doing some wierd things. I could tweak this by adding more or less traits to specific items, or adding special abilities...but the core game needs to be pretty simple/approachable.
On the armour side of things, we also apply how much coverage an item provides...does it only protect the head, the torso, or some other part of the body? Does it cover multiple areas? We get results such as a padded shirt costing 2 coins, a breastplate costing 12, and a military breatsplate of the Imperium costing 21.
These armour values might reflect the actual game balance effects, but they don't particularly convey the feel. A world of floating discs wouldn't see too much in the way of heavy armour, especially when characters have to jump from disc to disc in order to reach their next encounter...heavy armour should be rare, so maybe I need to add in an availability factor, but then again it would also be undesirable for that very reason, so people would want to sell it off cheaply...highly protective but light weighing armour would be exceptionally valuable.
Still lots of work to do here, but once the formula seems to be giving the right output, I should be able to plug anything and everything into it quickly.