if you are serious about playing and decide to stop at some point, you should know as a matter of course that it behooves you to find new owners for your drums, owners who will actually play them.
This is an excellent point - works if you're on a budget as well, instead of buying an Indo drum, find a good second-hand djembe from Africa.
I think my biggest ethical issue with djembes manufactured in places outside of the Mande region (I include Ghana djembes in this) is that there is a lack of respect and gratitude towards the originating culture. If you're going to manufacture djembes out of sheer love for the instrument and the culture, then why not at least pay a tithe towards supporting the teachers/culture that inspired you? That, to me, would be a LOT more sustainable that merely re-planting trees. By ignoring that aspect, manufacturers demonstrate that they have missed a very important lesson that the djembe culture has to offer us. Musicians and artists who dedicate their lives towards bringing a wavelength of joy and celebration into their communities deserve to be respected and supported.
The degree of discipline required for them to do this is monumental (I would compare it to the level of discipline required to become a Tibetan Lama, for example), and they deserve some kind of financial/energetic acknowledgement and support from the people who benefit from their discipline and dedication. Instead, I see many brilliant artists, master drummers even, who suffer in poverty. Even their own culture has started to move away from a correct position on this, in many cases, with the advent of Western values. I personally feel pretty strongly that many of those traditional values are something that ALL of humanity can benefit from, so we need to honour that whenever possible and however we can.
This goes for traditional values from MANY indigenous cultures the world over - this phenomenon of opportunistic business development failing to compensate the originating culture isn't just limited to the djembe world. It's a glaring symptom of how Western values are sadly out of balance.