Definitely going to replace my passport.. even if its just for my peace of mind... While i can probably explain to Immigration when i get there what happened.. i have also learned that immigration can be really strict, Sure I have only had experience with US Immigration.. but it still terrifies me
yeah its expensive that's for sure lol, its $250aud to renew it.. But add $111 fee for losing/stolen passport.
Not sure what the fee is if i accidentally "Damage" it.. its slightly falling apart already.
Personally, I don't think I would replace my passport in your situation. Obviously it depends on your life situation and the kind of travel you expect to do, but if you arrive at Immigration and can document that you are a genuine tourist with a life and an income in your home country then you should be allowed in after a few minutes of fairly detailed questioning. Not a big deal.
If you decide to replace your passport, then simply tell the Australian passport office why. No need to damage or "lose" your existing passport... It is perfectly acceptable to get a new passport because of an undesirable stamp in your existing one.