You could buy magic items in Middle Earth. You just had to be in the right place and have the right connections. Middle Earth magic isn't flashy, but a +1 keen Nazgul Bane dagger isn't that hard to come across if you really want one. The elves just gave the fellowship magic itmes (including magic rope), so presumably if they'd actually had money they could have bought some as well.
The fellowship was on a quest to save the planet. I think we can safely say that the elves had reason to give them items beyond a casual whim. As for a "+1 keen Nazgul Bane dagger" not being that hard to come across, we only see one in the Ring trilogy, and again, it's not for sale at the local McMagic. Heck, a simple mithril chain shirt is worth more than the entire Shire.
Seriously: these are the epic, world-saving heroes--Arthurian in stature. The Once and Future King, Aragorn. The Fallen Knight, Boromir. The More-Than-Human Wizard, Gandalf--heck, Gandalf is effectively a demigod. And, collectively, they have fewer magical doo-dads than your typical eighth level D&D party.
"Melnibone... do you really think that Elric
couldn't have picked up some items in his starting town if he felt the urge?"
If he did, he or his immediate relatives would be the ones making them.
"Conan... do magic items even exist? I can't quite recall. If they do, given the accepted method for him to lose everything between novels is selling it so he can have money to spend on wine, women and song, then it's definately possible to
sell magic items, and hence buy them."
The few times Conan got his hands on a magic item, he didn't wind up selling it. Usually, he wound up having to destroy it to stop it from summoning some big bad end-of-the-world demon type.
Not familiar with the Belgaraid.
A grand total of four magic items I can think of: the two stones that symbolize the division of all reality, the Sword of the Rivan King (which is more of a receptacle for one of the two stones,) and Cthrek Goru, which is the sword of a god. Despite this, the Belgariad is about as high fantasy as it comes.