It's more common if there is a "sell price" on the item. I don't know of 1E or 2E players who with 20,000 GP in their pocket (which was possible with the treasure charts in those editions) wanted to craft a magic item. It was way too restrictive and time consuming. They wanted to buy it. Not that the option was always available, but players are players. Such a common idea does not just occur at a few tables. The DM might nix the idea, but it's a fairly common idea.So continuing to site how this was so common and intended in 1e -as it was in 3 and 4e- is kind of...neither true nor fact.
The 1E DMG also discussed selling items in the "open market". Are people so lacking in NPC character motivation as to think that markets don't have trade in both directions?
The 2E concept that PCs and NPCs should never ever buy or sell magic items was a stupidly ludicrous one that totally ignored common motivations like greed.
If your game was so narrowly restrictive and did not have markets for pricey items, I can't help it. A lot of games did have it and I was in some of those games. It was rarely a "Magic Item Emporium Shop", but it was often a traveling merchant, or temple, or wizard's guild or whatever.
Btw, even before 3E, 1E had Alchemists in the DMG for hire. Forgotten Realms had a lot of magic items in the town material. Judges Guild had quiet a few (and the two City States had shops that handled some magical stuff). There were literally dozens and dozens of magic items listed in most TSR village or town products back in the day (like Gateway to Ravens Bluff, or Village of Hommlet). If an NPC was 4th level or higher, it was almost guaranteed that such a character had one or more magic items. How do all of these magic items get acquired without some form of trade? Did every single one come from an adventurer finding it in years gone by? There were some potion shops sprinkled around (Hommlet had one in Return to the Temple of Elemental Evil IIRC, but not in the original). The 2E Dungeon Master Option: High-Level Campaigns book had suggestions on how to have PCs buy magic items (not via a normal shop, but via haggling, bartering for other magic items, doing some type of service).
Of course not every DM allowed PCs to buy magic items, but many did. This was not a new idea that suddenly sprang into being with the release of 3E. The very reason that 2E DMG had an entire section on "Buying Magic Items" is because people were doing it in 1E. There was this whole badwrongfun idea in 2E that a lot of people here seem to jump on the bandwagon with as well.
Personally, I prefer plausible campaign settings, not implausible ones. The DM is still in control of how much wealth PCs acquire.