I'm with you Redgum. If you want to sell your photographs you have to do it at the price the buyer is willing to pay. There is little point in working out that your photo must be worth 1500 if the buyer is willing to pay only 150. Of course you can decide not to sell, but then you will get nothing. I sometimes sell photos, but I much prefer it when a customer offers a price rather than asking "how much do you want"? That always gives me the feeling that they are searching for the lowest possible price.
I think if this happens to me again I will ask them to make me an offer they think is fair and I will say yes or no.