For 50gb the thumbdrive is hard to beat.
Set a reminder on your calendar to update them every now and then.
I have about 300gb of stuff I want to save (3 generations of family pictures, yes we do enjoy looking at them, on the 90" projector screen, as a family, on occasional dark cold winter evenings!)
My solution is:
2 drives in the desktop: one 'main' and one 2tb set up just to backup the 'main'
1 external hard drive stored at work; updated every 3 months.
This way it is protected from drive failure, theft, fire, etc. Cheapest and easiest way i could come up with. Pretty happy about it.
The desktop is 7yrs old, was about $350 (Dell refurb) the 2tb drive was another $120 or so.
The external drive was around $75