Ethics of reselling it? 
You acquired it and legally and rightfully own it, right? It is to the best of your knowledge legitimate and you will list it accurately and truthfully, correct? There is nothing wrong with making some money on something that the market values higher than you paid for it. Congrats to you for making a savvy buy. You should be rewarded.
That being said, for my idea of value, I do have a buying thread and an open offer out for $2300 for a sealed legendary collection box. (link to thread). So that shows what I value it at, and would pay. PM me if interested.