"the price for an item is too high" - not a noun phrase. Actually, this is a clause, as it has a predicate of its own. "a bottle of water while strolling" - not a noun phrase. "A bottle of water" would be a noun phrase (a phrase that has a noun as a headword), but "while strolling" is an adverbial phrase that describes the verb "buy". "The same brand of bottled water" - noun phrase. The headword is "brand", and all the other words cling to it and provide additional explanation. "a pair of athletic shoes" - noun phrase. The headword is "pair".
Parentheses will be used correctly in landscaping, where the native names of the plants are provided. This is because, parentheses are normally used to enclose extra information.
