A number of factors have affected the property market in Greece. The Greek economy crashed around 25 % due to the austerity measures imposed by the Troika and has not really recovered since. Unemployment peaked at about 25 % overall and around 50 % for the young. It's gone down a little from that peak but I think that it is still the highest in the EU. Greek banks have around 45 % Non Performing Loans (NPLs) on their loan book so mortgages, or any form of credit, are virtually non-existent. There has been a significant number of repossessions that all appear on the market as distressed sales. In Crete a significant number of ex-pats who were working here could no longer find work so they returned to the UK often trying to sell their properties here. Before the crash there had been rapid expansion of the property market so there was probably over-supply when the crash hit. I am sure there are many other reasons.
The basic Greek tax bands on pensions and earned income is:
€0 to €20,000 22 %
€20,000 to €30,000 29 %
€30,000 to €40,000 37 %
> €40,000 45 %
There isn't a tax free band but there is a rebate of "up to" €1,9000 for a single person provided your earn less than €20,000. It is expressed as "up to" because you only get the full rebate if your assessed tax is more than that amount. If your assessed tax is less than €1,900 it would all be refunded. If your income is over €20,000 the rebate reduces by €10 for every €1,000 over €20,000.
Bank interest is taxed at 15 %.
In addition to income tax there is also a solidarity tax that is assessed in bands:
€0 to €12,000 0 %
€12,000 to €20,000 2.2 %
€20,000 to €30,000 5 %
€30,000 to €40,000 6.5 %
€40,000 to €65,000 7.5 %
€65,000 to €220,000 9 %
> €220,000 10 %
The solidarity tax is calculated as a percentage of all income. So, for example, suppose you had a pension that was liable for tax in Greece, one that wasn't, e.g. a UK government pension, and some bank interest. The income tax brackets would be applied to the pension liable for tax in Greece, the 15 % would be applied to the bank interest but the solidarity tax would be applied to the sum of both pensions and the bank interest. That should allow you to calculate what your tax liability would be if you became tax resident here. Property tax is around €450 on a 110 sqm house in a 500 sqm plot in a village. It mainly changes with size and location. In addition there is a council tax of around €150 on the same house. My water bill is around €6 per quarter but some areas are much more expensive than that.
Even if you did decide to come to Crete full time I would suggest renting for a year anyway. You might decide on an area initially and then later decide that you would prefer to be somewhere else. If you buy at the beginning, selling again could be difficult.
Please don't misunderstand me. I am not trying to put you off coming to Crete. It is truly a magical place and I have no wish to live anywhere else but it is important to come with your eyes open.