What is an expensive dry white wine?

It's impossible to give a definitive answer to "expensive dry white wine" without more context! "Expensive" is relative, and what's considered expensive to one person might be reasonable to another.

To give you a better idea, tell me what you're looking for:

* What's your budget? Are you looking for wines around $50, $100, or even more?

* What kind of flavor profile are you after? Do you prefer crisp and acidic wines like Sauvignon Blanc or something richer and fuller-bodied like Chardonnay?

* What region are you interested in? Are you looking for wines from Burgundy, New Zealand, or maybe something from the US?

Once you give me some more details, I can suggest some specific wines that might fit the bill!