I voted "sort of" as it came closest to what exists in my campaign.
Clerics/temples make minor curative items - mostly those that require a CL of 3 or less.
There are wizard types who make a living creating minor magical items - things like everburning torches, items to clean a stained outfit, potions to prevent hair loss or tooth decay, etc. Basically "household" magic for those wealthy enough to afford them.
Mage's guilds in large cities make a brisk business of selling magical supplies, such as spell components, inks for copying new spells into spell books, and the various and sundry things those with item creation feats need to create magic items. For example, if one spends 1250 gold to create Boots of Elvenkind, they spent the money buying some rare & exotic components.
If the PCs want to buy something out of the DMG, they don't go to a "shop," they go to a broker - a rich and well-connected merchant who will try to find what they are looking for, and arrange transportation of the item to them - which is of course, why items sell for less than they cost. The PCs have on occasion made a "friend" of NPCs w/ item creation feats, and have managed to commission some things on a one-shot basis, but the broker model is far more common.
That being said, PCs do have a chance to acquire some magic items. The campaign world is gearing up for a multi-nation war. IRL, nobility historically have financed military operations by selling jewels, gems, artwork, etc. The fantasy equivalent of that is selling magic items - after all, that cloak of charisma that's been in the family for three generations is nice, but what they really need is the cavalry and infantry its sale will finance.
There have also been occasions where the PCs have donated to one or another cause, or accomplished a great feat for a given organization, and were rewarded with a magical item as a "thank you."
Basically, I just have a problem with magic item shops being economically viable in my campaign. Never mind the huge theft target thay would be, it's just not feasible to have that much capital sitting in one's inventory, gathering dust on a shelf and waiting for some adventurer to buy it. So I came up with some more "realistic" alternatives.