Our mailbox database was about 100gb in total for 200 users. We had 500mb-1gb sized mailboxes. We decided to move to Office 365 and what a treat. Each mailbox is now a 25gig limit and we won't hear from the users anytime soon when it comes to that. We don't have to worry about storage on site or running an exchange server.
Does it cost more compared to having your own exchange box? Yes, but its worth it. Our users love it. My network admin loves it as well. I highly recommend it. -- My domain - Nightfall.net
Gmail is now working with google drive, if you want more space for attachements, or files you have to upgrade your google drive account.
p.s. why dont you cleanup your inbox or something. (who on earth needs to keep old emails up to 30gb...) OR -use dropbox. -use pastebin.com (with a user account) -use google drive -use an external drive (500gb is about 40$) -use a thumbdrive (take it where you want) just my 2cents.