DL - You don't need any level of digging to find wyvern scales... but my digging is at level 2 (6 second delay) which I think is also about as far as Trib made it, and I have found maybe a stack of scales EVER. You really can't count on these to be constant until much later, like.. thousands of stacks of greens and months of time later. You're welcome to give it a whirl though.
Oh, and coral is also 110k per stack, and they NPC for less than dragon gear. ><
Also, congratulations on 100 Fira, I just made it there myself
Oh btw, are you skilling on a gavial mask there... in your apron??? didn't think you could skill with items on, heh.