When is it cost-prohibitive to rebuy?

[Lottery Larry]

Is there a point where the amount of chips you get isn't worth the cost of rebuy-add on, if you bust out right before the add on period?

Something I was discussing with someone:
"he busted out on the last hand of level 3 (last rebuy). So he was able to rebuy twice for 1000 each AND do an add-on for 2000 so he started level 4 with 4000. Meanwhile the guy next to ended level 3 with 1025 (couldn't rebuy) but could add-on for a total of 3025. It almost pays off to totally bust out on the last hand if you are sorta low"

How big a stack is required to make rebuying back in worth the cost? Is it a ratio of the average stack in the tourney?

Thanks
LL