Assuming Windows 7, any external hard drive + Windows files backup should work for what you need. IIRC Windows backup uses non-encrypted .ZIP files internally (at least Vista did) so even if you stop using Windows you can restore backups manually. I wouldn't use any external drive that claims to have its own backup software (actually I format any USB drive I get before using it) because you end up tied to whatever the software is.
OEM hard drive prices are still high so you're right in searching for "pre-packaged" external drives - before the supply shortage a separate enclosure + cheap hard drive would be the way to go, but now cheap hard drives are hard to find.
It's a little complex but I've been using Cobian Backup for file backup because again it doesn't tie you to using a proprietary backup format:
Cobian Backup