Sorry not sure why it's quoting delboypass. I couldn't delete his quotation marks in my comment. Spot the newbie.
Just to make it clear the following statement is mine not his:
Stick with it Babo. I just paid 22% under valuation (valued in March 2016) for a property in Aberdeen after accepting a similarly low offer on my flat. I was up-sizing so didn't mind. I had been researching prices for about a year before I moved though so felt I had a pretty decent picture of what I believed to be a true valuation, rather than the figures picked from the air by the surveyors.
Not everyone's situation is the same though so it's just about finding the right deal/pragmatic seller. They are out there though.