My personal and family data (not including ripped DVDs etc) are about 1 TB. Mostly photographs and video with my DSLR so the files tend to get large...but I also have a ton of documents, app installs, and all sorts of misc data. I must admit I'd be curious as to what fills multiple external HDs for personal data but to each their own.
Good organization outweighs medium in my case. 2xExternal 2 TB HDs - primary and secondary...and then a third stored off site at my parents that I update about 3 times a year, so if the worst happens I'm 6 mons out of date, but its usually about 4. And thats if both my primary and secondary go down. Thats a cost of about $300 total and a little a bit of effort.
"A little bit of effort" is defined by how you organize. Backing up manually means I don't rely on software or a service, but it requires some forethought. For me I break it up by data type and usually year...sometimes I go one more by how that data was acquired (photos I add who took the picture). This is important because I put anything new into a diff folder so I know whats new and whats not. It took me a couple of years to get to the structure I have but I sometimes add small tweaks. The effort or time now is fairly miniscule.
What I'm trying to get at is this : if you're prepared to put a small amount of time in every now and again, with an initial overhead, you can do this very easily and cheaply.