I think this is a wonderful idea. I doubt you would donate to a benefit you know very little about. Benefits are usually advertised in different medias that give a reason behind it. If your morals don't agree with the benefit, generally your heart tells you not to give. Yes, there are scams out there.
I guess I think differently about making and giving things for benefits than others do. But, I bet I am in a huge group that will take the time and my expense to contribute towards a benefit. If I am giving, the labor and costs to me are minimal compared to what the benefactor may be facing. Doesn't matter if it is an individual, a family, a group, a cause, a community, etc. If I stand behind and believe I can do some good, my 'costs' matter very little.
Pillowcases are a great idea, as well as a nice basket of quilting supplies and/or a kit or two. Many would bid on those ideas. I have been to these silent auctions where there are minimum bids written on the first bid line, with a name of the giver as the bidder. You wouldn't need to apologize for not doing a quilt, simply offer another item and ask if they would accept it. If we can make a small difference in the lives of others, isn't that what it is all about?