I guess it depends on how much data you have to back up but I'm able to fit all of my critical items (as in, things I can't replace: tax documents, family videos, pictures, etc.) on a 16GB USB 3.0 flash drive. It's encrypted with TrueCrypt and I keep it on a keychain that's attached to my other equally important items (house keys, car keys, etc.). So it's pretty much on me at all times.
I do keep full multiple backups at home though. The flash drive is really for if the apartment burns down/gets flooded/blows up etc. The things I'm not including in this "critical backup" would be a pain to replace but it wouldn't be impossible. I guess if I cared enough too, I could just pony up for a larger flash drive.
*EDIT* Nevermind, looks like you have a couple hundred GB of photos, videos and not a couple GB like I first read.
*EDIT 2* Not a terrible price all things considered: http://www.newegg.com/Product/Product.a ... gnorebbr=1