Probably not. The government is currently facing this problem and finding it very difficult to resolve, e.g see this ekathimerini article
. In most areas of Greece there are so few properties changing hands that it makes it difficult to calculate the ratio of objective value to market value. The current objective values are known for all properties but in most areas of the country the market value is only known for a few and they may not be representative. The general view at the moment is that market values are now less than objective values and so the objective values need to be adjusted down to the market value otherwise property taxes are too high. In my experience market values in Crete have always been higher than objective values and still are. Given that level of uncertainty, i.e. you don't even know if it should be higher or lower let alone by how much, it is impossible to construct a guideline.
Take my own property as an example. I bought the plot and had a house built to my own requirements. The total cost was €195,000 but some of that was due to taxes, legal fees and estate agents fees so I don't know the exact figure. Lets say €180,000. All the Greek friends I have discussed it with say this was a reasonable and fair price not a "rip off the foreigner" price and, trust me, they would have delighted in telling me if they thought it was too high. If I take the absolute worst case change in the price index
, from when the house was handed over to me to present, for the whole of Greece, it would be worth a bit more than half that value today. Thus it should have a market value of more than €90,000. That is an extreme worst case low estimate so it is probably over €100,000. Based on other peoples experience, who have tried to sell their properties, I am pretty sure an agent would put it on the market for at least €150,000 but I have no idea what it would achieve. According to my latest ENFIA tax bill the objective value is a little over €66,000. How can you make any sense of prices at all with that sort of discrepancy.
I doubt if there is any point in trying to work out a sensible offer. Make an offer less than the asking price that would work for you and see what happens. If the owner is desperate to sell they will reject it but start to negotiate. If they are not desperate to sell, and the majority of Greeks aren't, then they will just say no and possibly increase the asking price on the basis that, if buyers are going to try to talk them down, they need to start higher.
There are also due to be online auctions of properties repossessed by banks for non payment of loans and it might be worth investigating that if you want a low price. There seems to be a number of delays in getting this system going and I don't know if there will be any in Chania but it might be worth contacting a lawyer specialising in property law and asking if they know of any and could they help you negotiate. See this article
and this one