You can find throughout Sapa town series of souvenir shops where they show all local people's products: handicrafts, silvers, wooden things. All products are made by the people in this region.
It is also interesting to go down to the villages and buy souvenirs from the local minority people.
It is important that you should buy things from the adults (especially from women) in their houses in stead of buying outside and from children. By this way, you will encourage the people to sell things in their villages and motivate the children come back to schools.
Try these exotic souvenirs instead...
How about some handicrafts?
Consider buying these unique 'luggage bags' if yours doesn't have enough rooms for the souvenirs