Thank you for going constructive - it's all too rare.
Y're welcome.
I absolutely agree 3E was far from perfect, and made several missteps.
But detractors all simply wash their hands, saying "that proves it's impossible". And WotC likes this idea (which is nothing less than pure FUD), because they (not so) secretly don't want to do the hard work.
In fairness it might not be because they don't want to, or don't see a need for it, but because of another problem - see below...
They much rather continue on the path to destroying the core gold hunt that is D&D - just look at Xanathar and the excrecable "treasure point" system. It's abominable to think this would ever be adopted wider than just the AL.
I haven't looked at Xanathar's yet and am, in the main, rather unlikely to. Can you give me a two-line summary on how the treasure point system works?
A much more constructive and positive way forward is to tackle the design issues right on. You mentioning the shopping menu nature of it all. We all agree that's probably not what was intended, but we also acknowledge that's how it ended up.
This situation demands that the system is complemented by a rule detailing availability, and not merely as a vaguely optional/variant rule either, but as something that's built into the core of the system.
Agreed. However herein lies the problem I mentioned earlier; see below...
And item creation probably needs the "formula" or "ingredient" solution, again as a core non-optional system, where you can't create diddly squat unless you have the items required (thus allowing the DM to veto specific items). I prefer ingredients over formulas, since with a formula, once you've opened the gates to a certain item, it can be manufactured over and over again. For some items, that's fine. For others, not so much. With ingredients, the DM can control not just which items that are possible to make but also how many.
Much more important than any of this, if PC item creation is to be discouraged (which would be my preference) there needs to be a big time factor attached. Potions and scrolls - they can be PC-done, within a few days. Recharging an existing device? Usually ditto.
Anything else? Start with 6-12 months construction time (includes sourcing materials, preparatory enchanting, actual construction or smithing, main enchantment, etc.) and go up from there.
What is absolutely necessary is much more robust DM assistance. What items are appropriate to hand out to your heroes?
If the rules mandates formulas and ingredients, it should also provide default recommendations. Something 3E never did until it was way too late. The devs did learn loads about the way the system worked (as opposed to how it was intended to work). And I'm sure Pathfinder ("version 3.75") have amassed even more knowledge.
So creating a second (third? seventh?) version of d20 item pricing and creation should be entirely possible.
You touch upon more points, but I'll stop here. My point is none of this is easy. Anyone claiming this could be whipped up by just some fan on DMsG is just talking through their ass.
And now we reach the problem I've mentioned above: DMsG - or some other online equivalent - is the only place this can go!
Why's that, you quite legitimately ask? Because the end result, in order to be the least bit elegant and-or functional for the average DM to use, has to be in the form of a purchasable computer program. A program that does the following:
a - has complete lists of all official magic items and easy instructions for custom or homebrew editing (deleting items and-or changing prices) and-or expansion (adding in your own stuff).
b - generates a number of random items (this number is input by the user each time) by weighted randomness - this hits the rarity issue - and their associated costs; this would be used when, say, determining what happens to be available in a given place.
c - has complete write-ups of all official items and properties.
In fact, this is hard. Very hard to calibrate just right. And time-consuming since attention to detail is paramount. The ones that ought do it is the core dev team of WotC.
And even the highest seller on DmsG reaches just a fraction of the audience of the worst-selling official 5E publication. To gain system-wide adoption (while still entirely opt-in), it absolutely must be in an official hardback like Xanathar.
I suppose if each book came with a thumbdrive containing the magic-items program it'd work, but otherwise a hardcover (or any) book just isn't the right medium for this - sad to say.
And WotC, no matter how hard they tried, wouldn't get this bang-on right the first time. However, if it's a computer program that's OK, as computer programs can be updated as and when errors are found and-or problems arise.
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To follow on from a post of yours further down, without quoting it all: I don't at all believe magic item pricing* should be - or in most cases even can be - done by formula. Each item has its own price, which may or may not be "accurate" in terms of utility and-or usefulness in the field; and I'm fine with that. Glaring errors can always be tweaked or fixed on the fly "You got that Ring of Invisibility for only 5000? Man, you got a deal - they're 8000 now!" and maybe someone might get lucky on a buy low-sell high hit - so be it.
* - exception: spell scrolls, where a by-level-of-spell formula is in most cases is all you need, plus material component costs.
And the same is true of a DM inventing a new item: just go ahead and bang a best-guess price on it. Time will tell if you've guessed too low, too high, or about right - and this would be reflective of whoever's first made this item in the game world - their initial price is also likely to be set by educated guess.
Formulae are way too constraining, IMO.
Lanefan