What is the replacement cost of batteries?

As we are still in the prototyping stage and have not entered full production yet, we are still working out volume pricing of our batteries. Based on current pricing, our standard pack costs about $2400, but we are hopeful that with volume we are able to get that cost down below $2000. However, keep in mind that battery research is proceeding very rapidly and for those who purchase the standard pack, by the time those batteries need to be replaced, better batteries will likely be available at a much lower price, so upgrading at that point may be more cost effective. Also, while battery replacement costs are substantial, there are very few other maintenance costs associated with the vehicle, not to mention fuel cost savings.