The Mockingboard is a wonderful piece of hardware and it's great to see them still being produced today. They're even available in kit form if you'd like to solder it together yourself (it's all through mount, nothing difficult).

I will note, however, that it's not just that the card doesn't ship with the speech chips (SSI-263P) - no one has made them in a very long time, and they're essentially impossible to find (and very expensive if you do).

Finally, if you're going to dust off an old Apple device and fire it up, I would seriously recommend rebuilding the power supply - capacitors don't last forever, and they can do unfortunate things when they fail.