Although 2 NiMh AA batteries run my deck for a long time, I ended up getting this power pack from Amazon, which has selectable voltage down to 3v. Saw it here somewhere, but I can't remember where:
Went to one of the many convenient, local radio shack stores, and got two adapta-plug sockets, a package of butt connectors, some shrink-wrap tubing and adapta-plugs "N" and "B" to make this hack-job power cable:
Turns out I also had this old rat shack 4xAA NiMh charger which plugs into the wall to re-charge itself and also has selectable voltage from 9v to 3v:
Both battery packs run the R-09HR, probably for much, much longer than I'll ever need:
and
Total bill at rat shack was over $26 for all the parts, but that DIY feeling was, well, priceless...