Each exchange's price is correct - it's just price variation based on multiple factors, similar to how a can of coke can be priced differently in various shops.

Each exchange's price is correct - it's just price variation based on multiple factors, similar to how a can of coke can be priced differently in various shops. E.g. if you intend to trade with MtGox, their price is the one you should be concerned with. Virtual currencies are still a relatively minor market so there's more discrepancy between exchanges compared to, say, mainstream currency or stock trading.