MAG (Mines Advisory Group) is a non-profit organization that centers on the humanitarian aspects of war ordinances. They strive to eliminate them from military arsenals, as well as clean up any ordinance debris left over and simultaneously try to assist in medical aid and rehabilitation for those people affected by them.
Visiting the information center is free. They display a lot of information of the conflict region and its clean-up efforts. Opening hours are 8am to 8pm every day (these may be reduced outside the Nov–April peak season)
What to buy: Charitable donations are very welcome.
Typically people will by T-shirts with the proceeds going to fund MAG activities.
You can purchase over the internet, but all goods will be in English. If you want your articles to be written in Lao, then you must purchase from the local centers.
What to pay: Donations can be any amount. T-shirts are about $10 USD with proceeds going to charity
Phonsavan has a very good local market right in the center of town.
You should try to visit it in the morning or at least before noon as that is when it's busy and the most fun.
This is not a tourist market at all, but a local market with local food and locally made handicraft that is made for practical use and in my eyes these things are very nice and genuine souveniers.
What to buy: There is a big food section, but also various handicrafts and a big clothes section too.