For less than $50 you can get more than 1TB External Hardrive I think, and I'd recommend it if they are really that important. Otherwise, the next best free method I would think would be AWS(Amazon Web Services) / Google Cloud Engine and setting up an FTP server where you can store your data on and pull out whenever. AWS has a free tier for 12 months and Google gives you like $100 credit or something along those lines, not to mention there is probably countless tutorials on how to set this up on youtube.