Setup a "saved search" and set it to notify you.
Refine it to your tastes, and prepare to wade through a lot of items. Be aware that bargains are often listed in wrong categories so set that criteria wide
Sooner or later some pups will come up that you can collect locally, or that finish at a silly time of day that you can win for not much. Be patient is my advice
The pup I got is used in some custom shop models so it was quite the bargain
Alternatively PM bass chat member matte_black who makes his own, I bought the split coil jazz pups which were awesome