Who says? The designers. They designed the game so that it could be played completely without magic items built into the underlying mechanics (unlike previous editions where you would fall behind in competency if you didn't get magic items ). Magic items are a bonus, and too many break the math of bounded accuracy. Even in AL, barring earning levels with a faction, you can't buy magic items. This isn't Pathfinder where the Magic Walmart is just down the street. If the intent is to play as close to RAW as possible, then magic item shopping is out. Magic items are COMPLETELY at DM discretion. Even Xanathar's doesn't say you can just find the magic item you want. Availability is supposed to be random and very rare.Who says? Listed in the DMG index is "Buying Magic Items pg 135-136".
There is says, under a chart listing prices by magic item rarity and by character level, "Unless you decide you campaign works otherwise, most magic items are so rare that they aren't available for purchase." So, RAI perhaps magic items cannot be bought. But RAW, there are prices for magic items. Why would there be prices for items that cannot be purchased?
Next, Xanathar contains a whole bunch of common magic items. Who makes a magic Pole of Collapsing in a world where magic items are so rare they cannot be purchased? Staff of Flowers? Really, a wizard is going to spend months working to make a mighty UNBREAKABLE ARROW in a world where magic is that rare? The existence of cutesy magic items (perfume of bewitching) runs counter to the idea that magic items are even rare.
Not saying there are shops with regular daytime hours. But one or more by appointment only "stores" in Waterdeep? They must exist.
Except now you have a FM say, "Sure, you can have a +3 Holy Avenger at level 1" and any One Shot DM now has to allow that brokenness, even if they wouldn't have given such garbage out.There are rules for the cost of magic items (and those cheap common ones I mentioned should be just 50 gp so run out now and get a Talking Doll ). And Xanathars has a whole page devoted to buying magic items and another page for selling magic items and nearly two pages for crafting magic items. But yeah, RAW you can't buy a magic item? RAW? Sorry, RAW magic items can be bought.
But also note: I didn't say anything about walmart in my post. I said, with the right contacts, you could find a "store" in WATERDEEP. You can BUY or SELL anything in Waterdeep. Why did you even mention walmart? See, a better argument would have been Pit Fighting, also in Xanathar's. Am I forced to introduce pit fighting into my world just because the book has rules for doing so? No, of course not, and you might have suggested that buying magic items doesn't happen in the One Shot compaign world and the group could discuss that. But RAW?
Finally, the designers. I even said in my post "Maybe RAI you cannot buy magic items." But just because the sacred numbers don't account for magic items, doesn't mean they can or cannot be purchased.
Bringing this back to the thread at hand:
Since there is no actual world outside the One Shots, I would think it would simpler to assume magic items are Commissioned. You state to the DM, in the recruiting thread of the next game, that prior to the adventure hook, you wanted to commission a Moon Touched Sword. If the DM approves, you arrived in the city where the adventure starts with the item (or are picking up the item there).
That's my suggestion. (And I still need to actually make some characters as I need to be in more games.)
Except now you have a FM say, "Sure, you can have a +3 Holy Avenger at level 1" and any One Shot DM now has to allow that brokenness, even if they wouldn't have given such garbage out.
The new classes in Xanathar's are basically RAW, but the rest is basically like the DMG. Nothing in it is needed for the game. It's useful, certainly, but even AL doesn't use most of it (yet?).Oh I di not know Xanathar wasn't RAW - that is good to help with Class D characters. We will just have to do what RPGer's have been doing for years and years. Come up with our own rules.
But not till after the holiday - everyone think on it, I'm sure we can hammer out something for this.