I'm sorry to hear about this guys as I know that some buyers do tend to be somewhat incredibly slow to pay and don't seem to bother reading the terms of the auction.

As a Buyer, I don't bother bidding unless I'm able to pay immediately (Usually within 30mins of auction's end) or I'm able to pay within the defined period set in the terms by the Seller.
I basically treat Auctions, even the sales here on the forum, as if I was walking into a brick and mortar - I don't express interest unless I'm able to pay on the spot or a Layby-esque payment method is available (i.e. Holding an item for an agreed time-frame).

Communication is a big factor for me when dealing with online sales and is why I do my utmost to be thoroughly communicative with a Seller - It's a pity that it seems a hell of a lot of other customers don't seem to take a similar approach.