How much to maniac? Unusual rebuy structure

[bismillahno]

Hi,

tomorrow I"m playing the south island champs event in Christchurch, New Zealand. Its got a pretty strange rebuy structure, $500+50 buy in, with $100 rebuys and a $100 addon. With rebuys being such good value, I should be going pretty crazy early, right?

To conteract this, I'm operating off a ~12k roll. When I initially bought in, I was under the impression it was a $550 freezeout, the website wasn't too informative unfortunately and I can't withdraw. I guess I'm just looking for a little advice as to how to balance such great value in the rebuys with being quite underrolled for the tournament.