The K-World TV Gamer Box (1440) sold by Maplin @ £40 in December works pretty well.
So far I've used it on my A600 and A1200 via the composite to my AG Neovo 19" TFT. The results are much better than connecting the composite to the TV card in my PC (plus of course you don't have to be firing up the PC - saves on the environment and eleccy bill a tad).
However, I have also used it on my CD32 via the SVHS which gives a quality of output very close to RGB.
It's so good that I'm considering doing the SVHS hack on my old A600 to see what that's like. If it's any good I'll then hack my A1200.
The TV Gamer Box also accepts component RGB. The most ideal solution would probably be to connect the Amiga to an RGB>Component converter, then connect that to the TV Box.
Having said that, I'd still prefer an all-in-one RGB>VGA solution. Hopefully Roy or Jens will be solving that for us.