I'm not sure if this is the biggest piggy bank ever in Egg Inc or not.... I would guess probably not, but it's pretty big. Thanks to many prestiges at Immortality, Tachyon, and occasionally Graviton or Dilithium eggs, I'm a little above 105,000 golden eggs in my piggy bank now, and I plan to crack the bank pretty soon once this Dilithium Farm slows down to the point that it takes too long to get more golden eggs into the bank.
Cracking this bank won't get me all of my remaining epic upgrades, but it should get me roughly halfway there. Then I plan to calculate exactly how many golden eggs I'd still need to finish them. Some of my eggs this time (maybe 4,000 of them) will actually be expended to advance time to get me a chicken-filled Dilithium farm so that I can put some truly great farm stats on my profile page (and see just how many soul eggs I'd get from prestiging with such a farm).
I will take a couple screenshots of myself cracking this epic bank, but I haven't uploaded pictures to Wikia before (and am not sure exactly how you guys got such clean pictures of the vehicles and habitats), so it's possible I won't upload them right this moment. Maybe I'll figure it out tomorrow or something.