Most of those boards coming from China that are being sold on ebay are actually just clones of genuine boards but they are all pretty much the same set up offering the same functionality. Loads of sellers on ebay but most of them sell the complete kit rather than individual items. if you cant find a seller that sells the pendant controller as an individual item then it might be worth messaging one of them to see if they will sell you just the bit you want. Sorry can't help with a seller who I could recommend though.
CNC zone or one of the other cnc sites might have some recommended suppliers listed though.