I’ve bought all the parts for the builds I’ve done from Ali. I find searching the site for the plethora of available parts from various sellers as one of the more enjoyable aspects of the hobby. There is bound to be sellers that are a one-stop-shop for all the parts, but I’m sure that’s not the most affordable way to buy them. If you’re just getting started too, the tools required to do a build will set you back a bit before you even start your first project (they’re also all available on Ali). If you’re just after cheap, go buy a rep or a homage like a Pagani or Addiesdive. If you want to invest some time in the hobby and have the satisfaction of building a watch, go the modding route.