A recent thread on ELL has raised a question in my own mind regarding something in an answer. Consider these two sentences:
All the computers in this section are the same price.
These watches are different designs.
An answer originally suggested adding "of":
All the computers in this section are of the same price.
These watches are of different designs.
"These watches are of different designs" is a construction you would routinely see in formal or technical writing. In casual speech, people would tend to leave out the "of". But the "of" sounds perfectly normal.
However, "All the computers in this section are of the same price" is something I would never expect to see in speech or in writing (at least in AmE). Looking at the words, they seem grammatically correct to me, and I can't see any reason why it would be wrong. But it just sounds totally unnatural for some reason.
I speculated that the reason might be that in this context, "of" is associated with being part of something larger or part of a set. "The same price" means that they're equal, which conflicts with that usage. That explanation seemed logical. However, even "are of different prices" sounds off, so I don't think that is the issue.
Addendum: discussion in comments makes the issue clearer. I'm not sure if it is "of" that's the problem, or the "are of" combination, which is commonly used with some words but rarely with others in AmE.
"Xs are of different designs" would be common enough, but "Xs are of the same price" would not. English Student comments that "are of different prices" is common usage in India, so it may a regional thing. Let me refine the question, then.
In AmE, some words that refer to properties or attributes, like "designs", "materials", "sizes", "ages", and "colors", all might be used with "are of" (although the "of" would likely be dropped in conversational speech). Others, like "prices", are not typically used with "are of" (off the top of my head, other examples don't come to mind).
Perhaps "prices" was not always an exception but fell out of use with "are of" at some point. But in recent times, "are of" and "prices" aren't typically used together in AmE. So my question: is there a pattern, rule, linguistic quirk, something inherent in the definitions, grammatical oddity, etymological basis, or other reason why this specific word, "prices", (and I assume some others), doesn't fit the normal pattern?