Another matter, that ties into two comments I got in the thread on magic item prices.
[MENTION=12731]CapnZapp[/MENTION] — I think you're overcomplicating things. Requiring the DM to both choose a curve, and potentially reprice everything relative to that curve? That's never going to fly. It's way too much work for way too little value.
I got a question.
some items are valuable at any level.
Ex. Weapon of warning, bag of holding.
Should we price them as level 20 items, since level 20 character would gladly pay for them?
My point here is a bit advanced, so please make sure you understand the underlying concepts first.
Some items are reasonable to give a static gold piece cost.
Some are not, and need to have a cost that is relative to the total wealth of the character. Or, in other words, a cost whose gp cost depends on the character's level.
Let's take an example of each.
*** First, the Longsword +1. In this example, we will be assuming we're using a more sophisticated damage resistance scheme than the default for 5th edition.
So, heroic monsters (CR 1-10) run as written; if they have damage resistance, a +1 weapon ignores it. Paragon monsters (CR 10-20) that the MM says have damage resistance really requires a +2 weapon. A +1 weapon deals half damage, just as a non-magical weapon does. And epic monsters (CR 20+) with DR require +3.
Now, if we say our +1 Longsword costs 5000 gp, that's a significant part of a 6th level fighter's wealth. But it's a trivial expense at level 16. But this is okay because the sword is essentially worthless for the level 16 character! The 4990 gold extra you pay over a non-magical longsword still gives you +1 to attacks and +1 to damage which is nice, but getting half damage is the obvious deal-breaker here.
*** Now, for our second example, an imagined "Ring of Attunement" which grants you a fourth attunement slot. This item is just as desirable at 15th level as it is at 20th level. (It may not be as useful at low levels where the three-slot limit isn't a problem).
What should it cost? Well, the cost necessarily is "getting to have less shopping money now, in exchange to more attuned items later on". Or, alternatively, "getting to have four weaker, cheaper, items now instead of having three stronger items".
So I'm arguing it should ALWAYS cost a fraction of your wealth. At 10th level, half of what a 10th level character can be expected to have. At 20th level, half of what a 20th level character can be expected to have.
The fact the ring will become cheap as the campaign progresses is of lesser importance. What's important is that it took away half your wealth when you bought it.
This is why the concept of price-as-level is so important and useful.
This is why the concept of wealth curves is essential to pricing magic items.
Link to wealth curve thread:
http://www.enworld.org/forum/showthread.php?619626-Design-amp-Development-Wealth-Curves
Link to damage resistance thread:
http://www.enworld.org/forum/showthread.php?620368-Tiered-damage-resistance
