$11 Rebuy.How much at first break would make the addon not worthwhile?

[Toddy]

Just a thought on this. Obviously if you have a huge bankroll you might as well spend the extra $10 no matter what. Lately at first break I've had between 6-15K which makes the add-on very important (15-33% more chips), but is there a number that would make it not really worth the money? Is there a point to spend an extra $10 to make your stack go from 41-43k for example?