my kids are the same way with the westbrookdog bully sticks. they can eat the whole thing in a single day 
 
i think nancy suggested the merrick brand bully sticks so i thought i would give them a try. i have purchased the merrick flossies but they went through those pretty quick too.  
well i LOVE the merrick bully sticks! first of all, they are individually plastic wrapped & vacuum sealed (which is rare and makes me feel better about quality control) and they last for a looooooooong time. as nancy said, they are more of a chew stick than a treat. i bought some last saturday and my kids have been chewing them every day - hours at a time sometimes lol - and the tip is barely chewed off 

 and they are not too smelly either 
 
i found a seller on ebay who sells them in large quantities (100 6" bully sticks for $249) and they also have a website with free shipping on orders over $75. i verified with them that these are individually wrapped and they said yes. i am going to order some after i pay my bills this month