I'm not much on the technical stuff, but can tell you that I love my 2011 EX (no Nav). Mine just turned 30,000 miles, and the only issue that I've had with it are the windows being a little slow to go up sometimes. I've had the right rear lubed a couple of times and it helps for a bit.
One of the most important things to find out about the car you're looking at is to check and see if the CVT (transmission) fluid and filter have been changed ever and, if so, how many times since new. Many of the people here change the CVT fluid and filter every-other oil change. I've been doing that, and don't have any complaints about how the transmission operates doing this.
I've not had any battery issues. Just a few weeks ago I made a stupid mistake on one of the coldest nights we've had in Florida so far this winter. Left one of the map lights on overnight, and discovered it in the morning when getting ready to do my first pet sitting job of the day. Was pretty worried, and imagined that I would hear the engine being cranked by the little battery for the first time.... as I understand it, the little battery doesn't do much if the IMA battery pack has enough of a charge. Well, thank goodness, the IMA battery pack still had enough left to handle starting duties and I, still, have never had the little battery have to start the engine.
The price you mentioned for the one you've located does seem a bit high. I'm not all that great at haggling (sp?) either, but imagine that you could print what you've located on KBB and other websites and take that as ammunition. Good luck, you will love the car!