Hey JB, idk what diggumup has, I got the Ziggy Stardust and an old '70's demo album of Heroes, from my local radio station from when I was young. Not really much to speak off..... lol. (may have 1 or 2 others).
I do have a dear friend who is a lighting and sound guy, he used to do lighting for Bowie (and some others). I figured he'd have all kinda paraphanalia from shows and stuffs. He told me yrs back, DB is a super nice guy and a perfectionist (said he had one heck of a lighting system, too, for the time).
I gotta reach out to him through his bro on FB. (The guy did 3 world tours with julio eglasias) And does not keep a phone, lol.