if you want to go wifi look no further than
ubiquiti:
http://www.ubnt.com/
and if you can provide los ... for your wifi link i'd go 5.8 ghz and then ensure if you have in home wifi you only use 2.4 it should keep any interference low.
however i do think the fiber option is a great thought ... you can get fiber pretty cheap pre terminated and whatever length you would need and instead of using it to extend network you could use it to extend the receive antenna's signal
http://www.skydreams.tv/SkyDreams.TV/FiberAnt.html
http://rfvenue.com/product/rf-optix%E2%84%A2
do not know the cost of the fiber ant, but the rf venue product is in the 650 dollar range ... yes i know not cheap but neither is putting an antenna on top of a mountain !!?? haha.