Quote -  External hard drives are not that expensive ;)  You can get a Western Digital 1TB external for a little over $100 right now, and that's a LOT of space.  (I'm not even going to say "It should be enough".  After the years of "collecting" I've done, I've almost filled up one of those on just backups.)

One thing about external hard drives - they tend to fail quicker than internal hard drives, and I'm convinced that's due to heat. So when shopping for one you should  try to find one that comes in a good, well-ventilated encasement, and make sure it has plenty of air flow around it.

And as far as external drives go, if you're putting important stuff on one, you really shouldn't buy the cheapest one you can find particularly if they're over 500 GB.