Gen 1 is as about as reliable as a car can get. As others have said, we're seeing Volts go multiple hundred thousands of miles no major maintenance issues. We've just turned 80K miles in our 2014 and it's only been a few oil changes, tires, and retightening of the axel bolt ($88). There was a drive shaft bearing prone to go wonky in the early Volts but that was remedied by 2014. The battery pack is crazy reliable. I think we've only heard about one or two packs ever having as much as a bad cell.
IMO, a 2014 Volt is the best used car for reliability, economy, and versatility -- period. Add in electric drive and all the other stuff and it's hard to say no.
On price... It's hard to provide a idea of value without knowing the options added. To give you some idea, when we purchased new, we paid $18,500 after tax credits for a Base plus Safety 1 (backup camera). $13,500 certainly isn't bad for leather, Safety 1 + 2, or other add-ons. For a base, I'd stand pat at $12,000 max. The general consensus is you really want Safety 1 (backup camera) and heated seats if you live where it gets cold so do consider those in the hunt for the right vehicle for you.
Don't underestimate your bargaining power right now. Many drivers are not aware of the benefits of electric drive and will dismiss a used Volt right off the bat. Others bought into the politically-ladened hype about $20K battery replacements. Most drivers today are looking for a SUV/CUV and won't even look at a hatchback. Add in the low gas prices and you have a perfect storm for a buyers market.