If a seller put "postage at buyer's risk" in advert and an offer was to be made - I would recommend a clear post on thread that any offer to purchase was on the strict condition of sale that the seller was responsible for the goods right up to their delivery in the advertised condition.

I say this because I did once pull up a chap on here about it because it wasn't legal to do so... And he said that he did accept responsibility for safe delivery, however it was the buyer's risk that the item could get lost or damaged and he would only receive a refund - the actual goods were not replaceable.
Seemed fair enough, if a slightly wonky way of looking at it unless it was an ultra rare collectable (which I don't recall it being).

Surprisingly this doesn't seem to be covered in a sticky... Might well be worth adding a note to one of them covering this perhaps?