The only reason we even offer a personal subscription option is because we know how impossible it can be to rustle up the budget and/or get administrators to okay an expense. I really see it as an option of last resort.
That being said, we have had teachers who opted to pay for their own subscription and then were able to show their department head just how valuable the service is. Our data reporting--especially when you use Common Core-aligned rubrics--is really phenomenal and gets administrators crazy-excited. Sometimes they just need to see actual data from their students for that "a-ha!" moment to kick in.