Instruments general marketplaces do not understand
Traditional instruments are hard to buy well. A general marketplace does not know what a surdo is, and the people who do know are scattered across the world. This is a marketplace of players buying and selling directly to each other.
Every tradition represented
Surdos, djembes, tablas, kavals and the rest - the instruments of the traditions taught here, listed by the people who play them. A listing written by a player tells you what a generic listing never does.
Player to player
Buying from another player means you can ask the questions that matter: how it has been kept, how it sounds now, what it needs. That conversation is most of what separates a good used instrument from a bad one.
Worldwide
The traditions are global, so the marketplace is too. An instrument that is impossible to find in your city is often sitting unused in someone else's.