Offering on a property

I would appreciate any view although I understand that there is no definitive answer. I have found an area I like and am thinking of making an offer. The property is with an agent and I have previously been advised that an offer of 25% below the asking price is not unreasonable. I appreciate that the agent has the vendors interests to protect and is unlikely to divulge the vendor's true aspirations. Can anyone suggest how I could go about establishing the true market value of a property? Many thanks in anticipation.

If you are looking on Corvera the best value propertues are the ones that are being offered direvtly by the banks, from €55k for an apartment plus we have one 3 bedroom apartmemt, fully furnished for €92k, rock bottom price

Recently 7 x 4 bedroom Nolga style villas sold for €130k each, again via the bank and are now being offered an €180k

If you are paying much more than this, even with the 25% taken off on your bid you are payomg way too much but it is unlike;y that you will get anyything like 25% more

To fully furnish a 2 bedroom property, including AC and everything you would expect to spend around €9k, plus on any property your additional buying costs are around an additional 12%

There is no such thing as a true market value, it is what the seller is willing to take because they would have paid over €250 originally for the property wich now is worh nearer €65k and this isn't just an issue on Corvera

Thank you Roy. IMy enquiry was more general and I think I may have posted on the wrong forum. I have been looking near Gran Alacant. Nevertheless, your comments are most helpful and appreciated.