Well trick number one is to buy a complete case. Trick number two is to buy them on the secondary market after someone has opened them. Trick number three is to figure out what the unique parts are and then feel through the bag to determine which one is in it. It will depend a lot on budget which method is best for you. I have used all three. If you want one of each then you can join the co-op here in the forum where I buy whole cases and then sort them into sets for people. It mostly works well except for the occasional case that is short a figure type.