10, 000 Opals
In Cass's Run, after you beat the Nano-Monster and Patchy, chop all of the trees in that arena down. Go to the 3rd yellow gate with a button above it, and shoot the button with a Mega Charge Boost from the Shadow Bunyip. A race to find the 4 triggers initiates, and these are the spots;
1ST- On the side of the building you entered, but the opposite end
2ND- right from the 1st one, but up high
3RD-On the rightmost waterfall, up high
4TH- left from the 1st one, but at the top
After you zap all 4, the yellow gate falls, letting you through. There are a few Cannonball Bunnies and a lot of Cass's Bunyips that can be killed right away with a Full Power Blast. At the peak of the mountain, there is a silver opal case with 10,000 opals inside. Since you can only get it here, come back every time to get it. If you are looking for opals for the Death Rang/ Doom Rang, you can go 3-8 times for 80,000 opals.
Added by: SamuraiRiver Apr 25th 2011, ID#33584