I bought this unit on eBay a couple of months ago. I also bought both sets of PatchMan music SoundBanks
http://www.patchmanmusic.com/rolandSonicCell.html which are WAY cool. I am still too much into the acoustic sounds of my Ketron SD4 to make much use of the Sonic Cell. If I were playing Funk or Fusion, it would be a dream box, but essentially I am a bebop, blues, bossas and ballads kinda guy. Some of the Brecker soundbanks are mind-blowing though. Instant Steely Dan.
I paid $465 for the Sonic Cell + power supply (manual is .PDF online) and sunk another $150 into the SoundBanks. I will entertain any reasonable offer before it goes on eBay. I really love some of the features (like saving my BIAB files with RealTRacks as .WAV on a thumbdrive and carrying a few hundred backing tunes with me.) It is VERY easy to blow my WX-7 along with the Sonic Cell without dragging the laptop along.
Also, it provide phantom power for a Condenser mike, so playing an acoustic sax along with tracks you essentially get a mixer with the deal. Anyway, if anyone is interested, PM me with an offer.