After reading CASA's website, I must say I am impressed at their philanthropy and their commitment to the welfare of children. It's really amazing.
For a craft (and having never been on either side of formal recruitment, I don't know how feasible this would be, so if it isn't I'm sorry) but I was thinking that you could possibly have the PNM's decorate the covers, or even the actual tops of CD's. On the CD's, you could record maybe your chapter president reading an inspiring poem, then maybe having them read a letter that the chapter wrote to the children, then maybe include a few inspiring songs? These could then be given to the children, because it would be a reminder to them that people do care about them and it would give music to inspire them through this hard time. I read on CASA's website how they are all about giving the children a voice, and this could be a really great way to inspire the children to use their voice.
In terms of cost, the CD's would run you about $150 for 800 (I found a website for wholesale CD sales, for example
http://blankcdmedia.com/) then the covers would only be about $30 for 1000. So would about $200 be too much for a recruitment craft? The recorded poems and letters could be done on a computer, and from what I understand you can burn a song as many times as you want onto a CD as long as it is for non-commercial use. Maybe I'm wrong about that, though. It would be mostly time-intensive, but if you had a bunch of sisters bring their computers and gave them each a certain number of CD's that they were responsible to burn and stuff, you could get it done in a few hours, although it would be annoying work.
Just an idea. Such a great cause though. Good luck on finding a philanthropy idea! Another could simply having PNM's writing a letter to a child who is being helped by CASA, and having them decorate that. It would be a lot simpler. =)