I must say that the pnm's for whom I've written recs have been very gracious and helpful with information.
Just to give pnm's an idea of what you're asking of an alumna who writes a rec:
* About one and a half to two hours of her time to complete forms, compose a letter, and print a photo.
* Postage to mail the rec in a large envelope so that it arrives nice, flat, and pretty, and for the SASE included for acknowledgement by the chapter.
* The materials (letterhead, photo paper, envelopes) to make this all happen.
* That she sign below a statement that says something to the effect of "I hereby endorse this potential new member."
That being said, it's time well spent for Panhellenic good will. As I wrote to one pnm, "Just promise me that when you are an alumna you will write recs too!"