There are no ATM's in mui Ne, Phan Thiet, or anywhere in Binh Thuan Province, Banks can issue cash advances on credit cards (Visa and Mastercard). The banks in Mui Ne - the Industrial and Commerical bank is next to the Tropical resort and the other bank is near the Swiss village resort) are usually closed Saturday and Sunday. The Industrial and Commerical bank in Phan Thiet (261 Tran Hung Dao street) may be open Saturday mornings. Bank close at 4 or 5 pm. This means that if you arrive in Mui Ne on a Friday, well it sucks to be you. Actually, tour office like Hanh Cafe can give cash advances for higher rates.
America Dollars are generally accepted in Mui Ne, But you usually get a better bargain using Vietnam Dong. It is nearly impossible to get change for something bigger than a $20 US. Try to carry lots of $10, $5 and $1 bills. The large the bill - the more it is scrutinized. Counterfeit money is very common in Vietnam. Locally, coins are offten not accepted. Merchants prefer paper bills.
If you are looking for alternatives to cash, we highly recommend Paypal. With Paypal, you can accept money from any one with an email address. They can send you funds from credit cards or even their own bank account. You can even send money to yourself. You can collect the money at any bank in Vietnam, or any other country with the Paypal Visa Debit card