Billy's Roland JP-8000 (ebay pic)

Analog modeling synthesizer w/ 49 keys (4 octaves, C-B), made from 1997-2001. Used on Adore and Machina.
[wiki]

Billy's JP-8000 went up on the Pumpkins' official eBay account on July 27, 2011. The auction ended on August 3rd at $760. The accompanying text read as follows:

Roland JP-8000 Music Synthesizer. Used by Billy Corgan on the demos for the Smashing Pumpkins 1998 Adore album and the 2000 Machina album. Serial #ZJ57318. Unit is in full working condition and does not come with any cables or manuals. A certificate of authenticity is included.

Information from the Vintage Synth website:

The JP-8000 Music Synthesizer has been designed using a first-of-its-kind Roland Analog Modeling sound source, combining the fat, powerful sounds associated with vintage analog synths with the flexibility of digital technology and MIDI. Like the classic Roland analog synths of the past, the JP-8000 sports a collection of 38 front-panel knobs and sliders for powerful real-time control, opening a brand new world of sonic possibilities. Innovative "Motion Control" feature memorizes all sequential slider and knob movements, ensuring that a great real-time "tweak" will not be lost. "Analog" synth functions like oscillator sync, ring modulation, -12/-24 dB filtering, cross modulation, an assignable ribbon controller and powerful pitch bend/modulation lever make the JP-8000 a very powerful synthesizer for live and studio use!