How many is bulk? 10? 20? And are you looking at prepaid? I'm assuming they are for temporary use but wanted to make sure
It depends on what you call bulk Paul and what type of account you are wanting with them? The post office for prepaid or an Optus shop for postpaid. If bulk means you are going to hand them out to all of your students you would probably best to speak with a business specialist.
As an alternative these students presumably all have access to mobile phones. You could perhaps offer to bump plans up buy $10-$20 which should give them enough data for the month.
Or perhaps organise parents to getting a 'school' prepaid sim. You can get a prepaid SIM of 120Gb for $150 these days that lasts a year. Pop it in and hot spot as needed.