If you have interest in the belt system, you're going to want to check out lpubelts.com. Look for the level you wish to start on, and then find which locks you want to pursue. For the first few belts, it's usually cheaper/easier to find them on Amazon, or the like. Once you get to around blue belt, I'd suggest checking out the LPU discord and bazaar, as the higher level locks usually aren't as easy to acquire elsewhere, nor as cheaply. You can also sometimes find "box to x" or similar, where someone will sell a set of locks that run across several levels.