Question for Lv 50 CRP

So I just recently reached lv 50 as CRP and am wondering.... where do I get hardened sap from? at the auction board that stuff costs a lot of gil, but where else can I get it from?
Google says that there's an area in each city where you can buy it, but I honestly have no clue how to get there.

:confused:

ah, thank you!
guess that option has just been too easy to think of!