The third option is that the bidder is one of those irresponsible ones who drive up the price with no intention of honouring their bids. They are a pain in the ass for both seller and well-meaning bidders.
About bidding on cheaper stuff first - maybe, but personally I have sold a few quite expensive items to bidders with low or zero feedback, but I've had non-payers as well
Look forward to what the seller has to say about his zero-feedback bidders
Let us know...