Should I cancel the order?

[dreamgirl7676]

I am fairly new to selling on Ebay.  I recently sold an Ipod touch - advertised as a 5th generation model.  After auction ending, found out that it is actually 6th generation, latest model and worth much more than sold.  I really don't want to risk negative feedback, but I also don't want to sell myself short of money.  The Ebay customer service rep suggested I message the buyer and explain, hoping to negotiate a difference in cost.  I highly doubt the buyer will be willing to pay any more than they have already.  Not sure if I should send a message or cancel the order, any suggestions?