I am not an expert, but it seems to me to depend upon what kind of music you play.
For Blues, you probably have what you need--I would guess A, C, D, G, and E are the major blues keys, and you have them covered for straight and cross.
If you are going into jazz or classical, then you should probably be looking into a chromatic one.
Anyway you can try this link.
It might put you in touch with harmonica enthusiasts not in this group.
There is also a newsgroup:
where you might post your question