25 in existence and I can't find a single seller on any trading website.

Only sale:

http://imgur.com/LZmHncP , http://imgur.com/kS9M38O , http://imgur.com/iz8pWJH

Sold for a Miami Nights Conquistador and 15 ref (The Conquistador was offered)

Conquistador mini:

http://imgur.com/lNwq25S , http://imgur.com/HTWD0AV

Offered on a TaW Degroot Experience (21.5)

Keys back then were 16.11 ref, so the math is

21.5*.9 + 0.93 = x

x = 20.28, rounding down to 20.

Can't find other sales for the life of me. If someone with premium wants to snoop around, go ahead. Feel free to tell me if I did anything wrong in the comments!

Forgot to mention there was another sale for a Stormy Storm Dragonborn Helmet, but I'm using that sale to price the Dragonborn Helmet.