MV housing has gotten insane since Google started their hiring binge in 2011. My rent's gone up nearly 50% since then. And Google's demographics are changing: average age is now about 31 (up from 28 or so when I started in 2009), so many of them will likely be having kids in the near future and driving up house prices even further.
Fremont is decent as long as you don't mind boring. Unfortunately, the commute over the bridge can really suck during rush hour (this applies to all the East Bay communities). Sometimes I'll take 237 around to Mountain View to avoid it, but both 880 and 101 have severe traffic issues.
A bunch of my friends actually bought houses in the Cambrian Park and Willow Glen parts of San Jose. These are still reasonably affordable, safe, and they're about a 20-minute commute down 85 from Mountain View. 85 is a parking lot between the Googleplex and about El Camino or Fremont Ave during rush hour, but opens up fast once you get past 280. If you're getting on at El Camino (eg. a downtown Mountain View office) and then commuting to San Jose it's not all that bad.
I've heard Santa Clara isn't bad either - it's 10 minutes from Mountain View without traffic (much worse in rush hour traffic, since it's on 101), but it's largely Korean/Vietnamese/Japanese immigrants and so prices have stayed relatively low so far.
All of these communities are really boring, with basically no downtown or civic events. One of the large factors that drives prices up are young professionals that want a high quality-of-life in addition to working at a fancy tech job.