I am trying to sell mine for 15K above value. The renovation costs 60K. Shouldn't the flat fetch at least 15K above valuation ?
No. The value already include your renovation. (Or rather it should, if the flat has been valued by a professional.)
Seriously, folks, what is all this "above value" business about? The value of the place is the current value, including everything that has been done. Why would you expect to get more than that? It's like you'd be willing to buy a car for 10K more than it is worth!
Of course, if a buyer wants it bad enough, you can probably get him to pay more, but personally I think that would make the buyer extremely stupid. Personally, I would NEVER buy anything for an amount above value, unless it was a one-of-a-kind thing and there was competition for it!