I've been putting together a list of links for parts for both the WPC 89 fliptronics and audio boards. some of the parts are getting harder to source so when I've finally found them from sources outside of digikey and mouser, I've been ordering quantity.
I will post what I have extras of when everything finally arrives for those also building their own boards.
I will also post my shopping carts links to make it a little easier to order. I was able to procure most of my parts from mouser.com but some parts are on backorder through 2023-24 so I've had to source them at places like:
(fliptronics board - TIP102, TIP36C)
pinball spare parts australia
(audio board - 4.7uH inductor, 4584, 74LS11, 74LS74, TL084, YM2151)
great plains electronics
(audio board - 74LS04, HC-55536, 74LC374)
(audio board - 27C040, 68B09E)
(audio board - LM1875, TL082, x9503, YM3012, 6264)