A dozen oysters is/are $4.

dozen is (collective noun)

In America, Punkey is right.

In Britain, and places where they use the British version of the language, they tend to use plural verbs with collective nouns. As in "The jury are going to give a verdict of guilty".

Don't know if they would apply this to oysters on a menu, but there might be a difference between the two versions of the language on this.

Thanks, Blickers.

There is no hard and fast rule whether to use is or are. The choice is often conditioned by the nature of the item that is being modified. If the item
usually comes in a set of twelve, such as eggs or oysters, the speaker chooses the singular verb; if the number of the thing is twelve, but it's not a widely recognized grouping, e.g. "how much are a dozen of these rose bushes?" the verb is plural. By the same token, we would say "do you think a dozen long-stemmed red roses IS enough of a gift to give my wife for our anniversary? but "I know a dozen people who ARE eager to hire you.". Thus I would choose 'are', and I would not claim that it is the only valid choice.

Another point - using 'is' or 'are' with prices is, certainly in British English, very casual and informal. Better to use 'costs' with singular items and 'cost' with plural ones, thus -

A dozen oysters costs $4.
A dozen oysters cost $4.

I'm (guys is that'n okay) sure Tang one of the others have pointed out that the spdrdr might catch the 2d (oops, second) that there are a number of menues labeled 'A dozen oysters'.....

Just kiddin' there above, Tang about speedreaders. However, if you've been following all the crit lately, do you think my foreshortening of your fine name might be one of those things we can no longer abbreviate....

Oopsd; critics, criticism, etc
Again lovya all....oops....