Two nearby martial arts stores are:
Dragon Connections is on Moody Street in Waltham, across the street from New Mother India. The day I visited, the woman running the store was also taking care of her four year old and baby. She was very friendly and helpful, letting me try various products and sizes. I found exactly what I was looking for. Based on my one visit, I recommend this store.
Silky Way is at 38 Kneeland Street, near Harrison Avenue in Chinatown. It was closed the day I visited. A friend recommends it.