After trying several car chargers, I finally found one that works with my N7. This is the link from Amazon:

http://www.amazon.com/gp/product/B008MS9XA0

And it's less than three bucks -- I wasn't expecting much for the price, but it works and it seems to be pretty well built for the price.

*** UPDATE ***

I guess I need to rescind my recommendation of this charger. It appears to be just a trickle charger for the N7 -- today, for example, my battery was at 70 percent when I started my commute -- the battery icon indicated that it was charging, but at the end of my 40 minute commute, the battery was at 67 percent.

It's really frustrating that fully-functional chargers and cables are so hard to find for this device. As someone who also owns an iPad 2, I'm a little mystified as to why the Nexus 7 seems to have standardized connectors, but doesn't support a majority of accessories...

I would say that it depends on how you'll be using it. I'm using mine in the car, for GPS, music, and other travel-related needs. I bought the 16 Gb model so that I could put at least 8 Gb of music onboard.