Tune,

I didn't buy it (tried, but it's pretty hard to find) but harvested it myself last spring. Then made blocks from it so it is a bit easier to put on the tang.

You have to harvest when the tree sap is running in the tree. Here in The Netherlands that's about the first week of June. It comes off the tree very easily, and harvesting does not affect the health of the tree. The bark grows back in about 6-7 years.

Hope you can do something with this info.