First, the shut down of Japanese plants has not stopped production at North American plants for the Asian automakers. So, the majority of the models people are looking for, are still rolling into showrooms. There are plenty of Camry's, Corolla's, etc.
Second, even the supply of those models built only in Japan remains adequate. But you wouldn't know that from talking with some people. Yes, because the supply of Prius models is tightening while gas prices are rising, the price of a new Prius has gone up. They are moving closer to list price and dealers know they can charge more for the gas-electric hybrid. That said, there's a distorted view some people are getting about what will happen with some of these models. It's an overstatement to think some of these Japanese models will be going up in price by three of four thousand dollars.