For the record I settled on a Sony TCM-210DV. The second-closest Staples to me had it in stock, so I picked one up tonight. For about $45 it seems like a nice piece, and the AC adaptor is included. I've already tested it out recording directly from the PSR-3000. The sound quality is what I would call "perfectly mediocre". It has automatic level-limiting which basically adjusts the recording level to the sound input, so if I play loud it will take it down a notch, and if I play low it will amplify it. In effect it behaves like a compressor more or less. The recording sounds good enough to present to the client as what they asked for, but not good enough to replace my live performance. Thanks Sony, and thanks for all the advice everyone.