Rebuy/Addon tourney question

[Scuba Chuck]

When you reach the first break, where you have your last opportunity to buy your addon. Is it automatic?

Do you make your decision based on your stack relative to the avg size?

For example the average stack in the the tourney I was in was ~ 8k. My stack was ~10k. Does it make sense for me to buy the additional 2k in chips?

Thanks in advance.
Scuba