Anyone who has the specialist knowledge to start an EV build that wants to purchase used parts like batteries, Tesla drive units and more will need to find a breaker.
I'm sure the odd part you will find on ebay from various places, however it does seem like the best place to get a range of quality used EV parts is https://www.evbreakers.com/ they stock nearly if not all EV parts, they have an EV shop and they even do their own battery swaps / upgrades for the Nissan Leaf'.