Reality Fracture has Commander brewers dusting off planeswalkers and building Superfriends lists again. If you are testing loyalty counters, extra turns, or a pile of new interactions, the card bill can get silly fast. I found Proxyprintery while looking at proxies Commander options, and it is worth a look before you sleeve up the whole experiment. Compare what you need, tune the list, and see whether your next big brew deserves a test run first, before buying every card outright.