Congratulations on the find and good buy! I went to a twice a month flea market in Nagoya last week (for the first time) and stayed until closing. Just before closing time I went to a couple of places that had odds and ends jewelry or what-nots on good looking old wood displays. I bought three pieces, one each from different vendors for about $10 - $15 each. One turned out to be what looks like amboyna burl. Another is very dark but smells something like a fir when cut. It is not as dark as my persimmon but the fellow said it was a Japanese ebony wood. I also got a fir tree burl that was very wormy.
All in all, I was pleased. There is some good pen wood at flea markets and garage/yard sales!