I suspect prospective buyers will have questions about the condition of the 3 year old battery, was it kept indoors at room temperature, was it allowed to fully disharge or did the owner run the bike and recharge every few months, I don't know about battery chemistry but leaving a lithium battery lying around unused for 3 years might not do it much good. Rad Power don't have the old batteries in stock so I imagine the next question a buyer might be thinking is will I need to have it re-celled. I thought the rule of thumb was to subtract the cost of a replacement battery plus any wear and tear, so if Rad charge $400 for the old battery or a recell costs $500 and you bought it for $1500 think if you ask for a grand a buyer might think twice when they can buy a new one for $1500 with a battery warranty, so Rich is probably right about asking for half price.