Although I really hope WotC never publishes an official price list, for several reasons (none of which have to do with particular animosity toward [MENTION=12731]CapnZapp[/MENTION]) what would be kind of cool is an expansion of the system in Xanathar's for buying/selling magic items to incorporate both location and another, somewhat arbitrary factor, to represent high/low magic. That is, a small village that happens to be very magical (e.g. a moon elf enclave founded around a magical well) will have different factors than a large, low-magic city.
The DM still determines, however he/she likes, what the average price or price range would be, but then generates not just whether an item is available (or a buyer is interested) and the actual price, but also the reasons for that availability/price. Which is sort of what the Xanathar's rules do, but without accommodating locational variation.