Once you get into the area where the Thermal Bunyip is located, run towards the left. 
There will be a 500 Opal bag. Go back out the way that you came in. You can get the 
door leading to the exit to open for you. Simply walk out the door, turn around, and 
go back into the room with the 500 Opal bag and pick it up again. Repeat this process 
as many times as desired.

FREEZERANG-8,000
LAVARANG-8,000
MULTIRANG-8,000
KABOOMERANG-12,000
OMEGARANG-14,000
DEADLYRANG-30,000
DOOMERANG-75,000
X-RANG-UNKNOWN AT THIS MOMENT