If you are coming to St Lucia, I would advice that you bring your credit card with you instead of all your monies in cash.
We use EC$ eastern Caribbean dollars in St Lucia so it is easier to use in St Lucia. There are some businesses that would not take US$50 and US$100 dollar bills because of fear of it being a counterfeit.
There are however, Stores at La place Carenage and point Seraphine who quote their prices in US$ bills. Those stores especially cater to tourist who come to St Lucia. If you have eastern Caribbean dollars then you can use it anywhere in St Lucia.
