Korg DTR-2 (ebay pic)
Rack-mount digital tuner by Korg, introduced in 1994. Includes a foot-switchable mute button for silent tuning.
[Korg tuner timeline]
Placed on the Pumpkins' official eBay account on 2011/09/29, ending on 2011/10/09 at $120. The accompanying text read:
Korg Toneworks DTR-2 Digital Tuner. Used by Billy Corgan. The unit has an attached power cord and has been kept in a smoke-free studio environment. No additional cables or manuals are included. A certificate of authenticity will be included. Unit is sold "as is".