I've been meaning to take a look through my Mollenhauer and Moeck catalogues. I think they may sell recorders in D, but I'm pretty sure not in the school grades. It's really only the beginners' recorders and the plastic ones that are especially cheap.

The problem I have with diatonic harmonicas is that I really don't like the missing notes. Hohner has one model with a complete low octave, but only in C and I don't know whether the top octave is complete or not; probably not.