For poor kids, they can still enjoy halloween. It doesn't cost a lot to make a good costume, throw a few bits and pieces together and there you have it, a great costume.
I agree ... an old sheet and a pair of scissors, and you're a ghost. Or a roll of toilet paper, and you're a mummy.

They had all costumes dirt cheap at Walmart after Halloween here, too.

I'm not saying it's not a good idea to donate costumes, it is. I just remember as a kid, we had the most fun when we were creative and made our own costumes for pennies, rather than buying them.