One comprehensive blog about apartments for sale and for rent in Turkey and in Istanbul is Apartments in Istanbul. The blog, although it is named Apartments in Istanbul, provides information about many places in Turkey including Marmaris, Datca, Akbuk, Didim, Belek, Bodrum, Antalya, Alanya, Kas, Kalkan, Yalikavak, Gumbet, Torba, Cesme and many others.
There is a great deal of difference in buying a holiday villa in the south part of Turkey and buying an investment property in a major city like Istanbul. The posts on Apartments in Istanbul blog are related to both and provides in-depth information for investors of any size. It is worth a quick look whether you are looking to buy a holiday villa in the south of Turkey or an apartment in Istanbul or Izmir or any other larger city.
The blog is written by expats living in several different cities in Turkey and all writers, some of which I know personally, have extensive experience in both living in Turkey and investing in real estate.