TL;DR: give syncthing a try. first time setup is odd, then bam, your files magically sync anywhere with internet.

I carried around my 1GB Data Traveler flash drive with great conviction. Then, a massive 4G SanDisk drive I would 'never fill up'.

Then, when my 16GB Nexus 4 filled up, one day while I was MTPing my old pictures to my computer, someone told me about Dropbox and how it would sync my pictures for me. After living out of Dropbox for all my non-cold-storage files...I hit the free limit. But I was a student and didn't have money to pay per month.

Skydrive gave me 25 GB. And 3 successive phones ate that like candy. So start paying up Mister. ugh.

But then, Syncthing came along here on HN. I installed it onto my phone and pc for camera download. then another, and another, and a separate folder for sharing files with a colleague, then my work SAN got laggy and lost files, so syncthing to keep my work files local and synced between work devices to the rescue.

And now, I don't pay for storage. or I do, but it just happens to come with word 365, but I don't bother using it.

And the flash drives? I'm up to a 256GB Sandisk Pro of some kind, but only for 'just in case' scenarios. Syncthing handles all of my LAN files access needs.