Well, I'm a Weiss/Barto fan too as it happens, and when I search in 'Unlimited' on the Amazon Music Player (not the web player) on my Macbook I find all 11 volumes of this wonderful stuff, plus the Dresden Manuscript duets! There's a 9CD set of Maria Grinberg's Beethoven too. I'll give that a listen on your recommendation Jerry!
Edit: The 9CD Grinberg set is only in 'Standard' format but there are also 7 of the individual discs in 'HD'.