I just got to a Rear-Guard and haven't been back to Rabanaster yet. Cool that you can buy them there. I still have around 15 or so, saving them for later. I did however get a bunch of teleport stones from getting a really high combo from the Ogii-Yensa (spelling?) Sandsea.

Those Yensa-Soldier type things that you fight when you first get onto the refinery. I just kept going from place to place and back again and ended up getting like a 49 chain. It was great!