You can come over to Tak Bai by taking a boat from Pengkalan Kubor in Malaysia. In Tak Bai you can walk around the local market and shop for stuffs like pots and pans, imitation T-shirts and cheap groceries like rice, mangos and vegetables. Many Kelantanese from Malaysia comes over here to do their marketing as it's cheaper here. But note customs regulations still apply. I think there is some limit how much you can buy and bring back to Malaysia without being taxed.
Remember to bargain hard. The people in this small Thai town speaks Malay in the Kelantanese dialect. This sounds very different from regular Malay but you can get by with maybe a calculator or some hand gestures.