I remember RetroGames, I bought my first turbo duo system from them back in 1999 or 2000 when I got back into turbo gaming. It took a couple of months from the time I placed the order to when it arrived on my doorstep. I remember calling them several times about it.
If you don't mind picking up a pc-engine cd rom2 version, I got a couple that need fixing, just haven't gotton around to them yet. Also hitofjapon on ebay has some clean looking ones that usually just needs the middle gear cleaned, relubed or just replaced, I bought three from them and all easy fixes, maybe I was just lucky;)