seems to be a lot of angst and complaining over a very trivial thing to me, present company exempted of course, but its usually the people that buy and sell on the forums as side buisness (buy and flip!) that most often complain about "PM sent", because it somewhat slightly hinders the benifit it provides sellers, to 'screen' the buyers and possibly get a higher price or sell to someone (else) closer (?).
the answer and alternatives are simple, when someone leaves a "PM sent" in your advert, you can reply, as is customary and accepted etiquette with a "Still Available". on many forums that also provides the seller with a bump to the top for thier advert which is advantageous to the seller!!..
as for prefering to sell to someone closer (or other such reason) that replied, at a later date, than someone offering to purchase first, within the parameters (inc price) of your advert, usually strikes people (buyers) as unfair DUH!, which is another reason why they leave the PM sent sign.
if the seller prefers to sell to someone closeby, stipulate it in the Ad or better still, sell via a different medium that is designed for local, instead of using the wider market to collect the higher price, when in fact you dont have any intention to sell to that market!...in other words, if you advertise worldwide or nationwide then you take first come first serve--pot luck and stop whining!