I think you have taken the first step by posting your intent and collection. I have purchased from both auction house and directly from an individual. I think it is advatageous for a buyer and seller to interact if possible. The auction house makes money on both ends and the difference between what the buyer pays and the seller receives is a considerable amount, in the realm of 30%, give or take 5% or so. I would be interested in your Holland rifle, if in fact you decide to sell it.