my guy is 9 1/2 inches maybe 4 or 5 months old. With crickets I always get the 1/4inch size because they grow so fast. My beardie eats at LEAST 100 bugs a day. I try to limit him as he gets older now but easily if I put more in he would deffinitly eat all of them so for me 100 crickets a day 1000 would last me only one and a half weeks. Do the math of how many yours eats on average a day, then add an extra 100 in case he wants more some days, an extra 100 to last for the days your inbetween shipments and then an extra 100 that will just simpy die. Every day I swear 10 or more die no matter how clean I kept the tank. I kept ours in a 10 gallon fishtank with screen lid.
Personally I recomend ordering cockroaches in bulk...not crickets. Ever since we switched to cockroaches our guy LOVES them so much more, they do not eat eachother or bite the lizard and they are easier to hunt, they live 4 times as long, are kept the same way, are the sme price as crickets and actually are healthier.