I have discussed this need with a number of barrel brokers (we also use barrel brokers to sell some of our whiskey casks).
The biggest issues I've had with using them is not knowing 1. the source and 2. how long they have been empty. Eliminating the brokers ensures we get fresh casks from people we know.
There's nothing we would like more than to work with a wine maker and be able to say our whiskies were finished in their casks. Cross promotion.