How much should I sell used Chanel glasses for?

I am thinking of selling a pair of worn Chanel sunglasses. What's a good jumping off point on a website like ebay?|||If they are in nice condition try selling them on Ebay for 75% of what you bought them for that way you get a good chunk but the other person feels their getting a bargain, too! Make sure to offer simple things like a refund if they want just in case.|||If they are in nice condition, sell for 65-75% of what you payed for.