eBay gets quite a few of these. Here, for example, is a 12.5 carater offered by a dealer that's trying, so far unsuccessfully, to get $100/ct. for it. This same seller has quite a few of them for sale of various sizes and they seem to occasionally sell one so this gives you a benchmark on how and for how much someone else is choosing to sell them. Your results may vary and, of course, ASKING $100/ct isn't the same as getting it. Selling is a skill.
no idea what they go for these days but 6-7 years ago saw a dozen treated black diamonds each the size of a dime for $50 each at a gem show with no buyers interested in them.