Hilary, thank you as always for the clear explanations of procedure, thank you less, as always, for your 'agent sell' although it provides amusement and I don't blame you for giving it a go.
We have been along this road many times so best not light the fire again but a couple of factual thoughts.
Following my Greek lawyers advice I got power of attorney, while in UK, without signing anything in Greece in less than one week; that involved an email, a visit to my local solicitor to witness asigniture (ú5) and sending the signed document to London with an SAE and a cheque (ú12). I would say it took me in all about half an hour of my time so where you get 2-4 months I don't know.
3 days of solid viewings with an agent then a decision, OK if thats what folk want to do, how about a cooling off period, how about visiting out of season, how about when back in UK thinking where was that boundary or are we sure that blasted olive tree wasn't in the way? I'm not disagreeing with what you say but saying there are other ways to do things also and they are not necessarilty going to end in disaster without an agent.
You can find shed loads of land/property for sale privately and an agent isn't necessary, but I agree that for most people an agent can smooth the path towards completion. Most of the plots I looked at were not in the hands of an agent, in the end I chose one that was, mainly because of the plot itself, not the comfort factor of an agent.
Think in UK, if you saw a house for sale privately, you went and looked and liked it, would the fact that it is not with an agent put you off, I think not, more likely you would be thinking about the saving of the agents fees.
As for your last paragraph, are you saying that the agent sets the value of the land at a fair price for the benefit of the prospective buyer....? The price asked is certainly not written in stone, you must make a personal valuation for yourself in light of your knowledge and understanding gained through looking at other properties and also take into account agent or no agent fees, backhanders etc etc. I've come to know of agents who regularly bump up the asking price by many thousands of euros, the whys and wherefores I don't care about, in the end I would only offer what I believed was a reasonable price, if others get caught out then more fool them,.... afto ine zoi, ... yes.