No question about it- St Maarten is the best place to shop. Everything is inexpensive including topical night wear! It was plentiful for the adults and kids and was only like $5 or $6 bucks!! I would wait and buy it there instead of searching all over and then paying for something that you might not wear again. Also- it is less htat you have to pack!
St Thomas is more expensive and they don't barter. Everything is price controlled there-