I have a TC-20E III I purchased from a fellow Nikonian in October that I no longer need as I've sold the 70-200 I used it with. The TC was originally purchased from B&H in May 2012 and has been used sparingly, I only mounted it once or twice.
Asking price is $375 plus shipping. I can provide pictures on request but all elements are clean.
I've sold a few items here on Nikonians and have been on eBay since 1999 with 100% positive feedback - http://myworld.ebay.com/mtparadis/