How do 99 cent stores sell goods so cheaply?

• Stack 'em high and sell 'em cheap - they sell large volumes;
• Loyalty - the idea that goods are cheap keeps customers coming back (apparently);
• Maximise margins - consistent costs (so no relabelling) and no additional fancy costs;
• Buying power - most 99c shops were I am have dozens if not hundreds of stores so they can push for lower prices;
• Smaller units - less for your dollar than two dollars gets you somewhere else;
• Efficiency - such shops tend to be ultra-aware of what sells and what doesn't;
• Sometimes it's also about selling stock acquired cheaply because it is expensive for the seller to keep it or dispose of it.