When you get here. Ask banco de cambio what rate of exchange is. Act like you have dollars. When you find out rate, tell him you want to change tranvelers checks. If he says rate lower, tell him you are going someplace else. There are lots of bancos de cambio in Sosua. If you don't want to accept the rate the first person was going to give you, follow same procedure at others. Likely one of them will give you the same rate as for cash.