At least in my experience, grad students don't pay submission fees. It usually comes out of an institutional finances account, typically assigned to the student's advisor (who is generally the corresponding author on the submission). (Not that the waiver isn't a good idea — I just don't think the grad students are the ones who would feel relieved by that arrangement.)

Also, I'm pretty sure my SIG requires LaTeX submissions anyway... I feel like I remember reading that at some point when I submitted once, but I'm not confident in that recollection.