Well,...
She does seem on the level, and IMO the unit did come from a church. [People are stupid about what they throw away, when the word 'digital' is flashed in their faces].
Having already had my preliminary discussion with her, and fortunately finding a pic of a PS-520 to send her for reference, I feel halfway confident that she can go back to the source to find the p/s [AND CABLE, as I emphasized, several times to her]. I'm optimistic, & hope for the best. It stands as good a chance as any to work out great.
The question of whether the M520-less-power-supply is worth all of $96,... well,... yes, of course it is. Whether I could procure a PS-520 and cable by itself is less of a sure thing, but might be worth gambling on. That's the unknown factor. I've been on Ebay for all of 3-years, hunting audio gear, and I only remember ONE PS-520 EVER being auctioned. Those aren't real good odds, IMO.
I believe
the M520, complete and as-new, would have cost ~$8,000-$11,000, minimum, [est],... and $96/used is a great deal, almost any way you slice it, and is still probably a favorable deal without the PS.
She's gonna hunt the PS-520 and cable down, and I hope for the best. After all, this came out of a church, and we all know church-people would never cheat anybody! [Ha-, yeah right]. Anyway, I'm still optimistic the ps & cable can be found, and am hoping for the best.
/DA