We do it about as cheap and low-down as it gets - we use our $50 router, that has a USB port on it. We keep a 2Tb USB hard drive connected to it, and all its files are available over wifi. On our tablets, we use apps like VLC and Infuse to watch streamed movies. Was just VLC, but the newest app update is giving us problems, so switched to Infuse and I like it better. Our TV is wifi-enabled, so it just connects to the router automatically and we can watch on that. We don't stream music from it, but that also works.
We keep the hard drive well-organized, so the simple user-interface of these apps is easy to find stuff.
The downsides are that it is not a full-fledged media server, so it will not go on the internet and pull down all the metadata, etc. It is a simple user interface - it lists files, where a media server has a more rich interface. There are only two of us, and we rarely watch different stuff at the same time, so the router has no problem serving this. For multiple connections greater than 1 or 2, it likely wouldn't work well and require a true media server. It is not greatly expandable. The router itself says it only takes 1Tb disks, but we have no problems with our 2Tb.
The router we have is this one: https://www.target.com/p/netgear-n60...4873&jb=180664
If you want to make it truly rugged for onboard use, then solid state drives would be the best.
All of our computer storage/backup is done on portable hard drives.