Sorry for unearthing this topic almost more than one year later, but I have a solution to your issue, which was not available back then.
https://deLouvois.com allows you to buy and sell art and luxury items for Bitcoin only, antiques included.
Earlier this morning, I listed a painting by Damian Hirst for a private collector only willing to accept Bitcoin, yesterday I added 3 high reliefs sculptures, a 1924 diving helmet and two 45 and 55 years old bonsai trees.
More and more people are coming to us because of Bitcoin popularity and the fact that the ebay/paypal combo is becoming an unpopular failing piece of garbage.
Hope that answers your question.