It depends on where you are, out here in Southern California, there definitely is a direct link to the price a Leaf sells for and the health of the battery.
It will also depend on the model of the car, but in general, you will always get a much better price for the 2013 models and newer since they have the 6kw chargers.
For example, with a new battery in Southern California, a 2012 will sell for around $8,000 and a comparably equipped 2013 for around $10,000. If the battery is degraded that drops significantly, for example, I bought my 2013 with 10 bars of battery for about $6,000 and last month it dropped to 8 bars, so I got a brand new battery. You won't get what you paid for the battery, if you bought it, but it will be more than what it would sell for without a new battery.