maybe add in something that will entice someone here to sell. These are big ticket items and the seller fees are likewise hefty not to mention shipping. Adding your location might allow for a local deal to avoid the risks/cost w/ shipping.
I think the key is to mention you're willing to pay market prices...becuz the default assumption here is that everyone posting here wants a BPers discount...which is normally alright for sets in folks inventory; but you're ask list are highly prized items that will sell easily at the right price so folks are holding them for a reason. Give them a better reason to sell.