I paid somewhere around 250 € for a Turbo Duo including RGB mod, JP-mod w/ switch, two Duo controllers, a clone multitap, an RGB cord, but no power adaptor. The case was in good condition with very few light scratches. But when looking at the inside of the console, the mod jobs where executed not that well, with room for future breakages. At least there was no hot glue involved. Months later, I had to send the console to a friend for the inevitable recap.
Keep in mind that this was in Germany 2 years ago, where any Turbo related stuff is harder to come by than in the US or Japan.