Like others have said, I've received many requests for donations, but usually it's along the lines of, "We'd love if you could send something - anything - for..." Occasionally they may be specific in terms of what's useful ("Would you be willing to donate a ferret item to our ferret shelter's fundraiser?" kinds of thing), but again, they're willing to take any item they can use. I've not had someone insist on a given item. That seems a little shady to me.
I also make sure that I can see the cause represented somewhere online. The ferret shelter sent me a link to their website, others have sent me blogs to check out... something that shows that there's a least a shred of legitimacy going on.
What you've got there? Sounds a little ... off to me. And it annoys the crap out of me, personally, when people would capitalize on people's compassion for sick kids. Argh.