Go to Menards or Lowes or the like and pick up a box of Cat6 cable and some wall plates to run the cables into or some Cat6 RJ 45 connectors and make your own cables. Not too expensive and YouTube will show you how to do it. (there is a color scheme to the cables, not hard and make both ends the same and you are good to go!) May need a crimper or punch down tool depending on which method you use. I agree with the fact that fiber cables would be nice, but I don't know how necessary they would be. Network switches and other devices that accept copper cables are cheaper and more readily available and with runs of 100 feet or less, a copper cable would do just fine. I believe a cat6 cable will do up to 10Gbps over that distance which is more than plenty for streaming videos and transferring data and other such things.  In my house, we do a lot of streaming and a few select online games (4 children) and I have a 1Gbps network set up and that is plenty.  All new cable I run is Cat6 to allow for the faster speeds someday, but my network devices are just set up for 1Gbps and that makes them cheaper. I've included a few links from amazon but most things I could pick up at my local Menards.  $175 or so and you could have a cable ran to all of your buildings.  

10Gbps Ethernet Switch
Punchdown Tool
Keystone Jack for Wall Plates
RJ45 Crimper
Cat6 Cable
RJ45 Connectors