The Riel is the local currency. Cambodia, especially when compared to nearby countries like Thailand and Malaysia, is a very cheap place to travel in. Accommodation is cheap and Food is also inexpensive, though transport- and more particularly long distance travel- tends to be a major expense. If you’re carrying US$, you shouldn’t have much trouble- dollars are widely accepted as are Thai baht and you won’t pay any more than you would if you were paying in riel. On the whole, the country’s a good option if you’re on a shoestring budget- and the widely accepted habit of bargaining for virtually everything and anything makes it even better.