There are cheap and good quality apartments here:
https://renthouseistanbul.com/

Hello, We offer fully furnished or unfurnished apartments for rent in Istanbul. Whether you are looking for short or long term units, we have varieties of options for every budget. Call or drop an email to us to have instant communication to our certified and multi-lingual consultants.

https://www.istanbulestate.co

I have fully furnished and Bosphorus view apartments in BESIKTAS CIRAGAN for expats in istanbul.

You can get our offer from www.apartrmentinistanbul.co.uk

You should also add erasmusinn.com I use them on my expat in Istanbul.

Thanks to contact me to help you in your research of accomodation in istanbul. I am french and working in istanbul since 1998 .
I do relocation assistance and I find your accomodation according to your criterias and budget .
Also , same for office .
Dominique Atay
Expat-Turkey

I specialize in finding foreigners accommodations in Istanbul. I'm half American half Turkish, just graduated from the University of Pittsburgh (Bachelor's of Arts in Sociology) in April 2012 and am working in real estate for the summer. I have been coming to Istanbul since I was little, I have family living here, and I can make sure you find what you are looking for.

Email: gcam5290@gmail.com
Facebook: www.facebook.com/gcam5290
Twitter: www.twitter.com/camerongracie

Finding a place to stay, especially in an unfamiliar place, can be complicated and confusing. Whatever you're preferences/needs are, I'm here to help. :)

Hope to hear from you soon.

CityApartmentsIstanbul specializes in brokering long-term rental accommodation in Istanbul. We can offer a wide range of accommodation, covering most tastes and budgets.

Flats or houses are available for lets of minimum three months at rates which vary according to the length of stay and conditions of rental. Whether you are looking for cheap or luxury rentals, we can support you.

CityApartmentsIstanbul can help you find the perfect housing solution, whether you are relocating, look for corporate accommodation, start working or studying in Istanbul. There are no initial expenses, contracts or tie-ins. Please visit our web site http://www.cityapartmentsistanbul.com

We would like to offer you some furnished flats for rent inIstanbul
We have 100 Elegantly Furnished Flats.Please visit our website for the flats.You can also see some wonderful photos and videos from
Turkey.

http://www.turkeysweethome.com/

Here is a link for Nisantasi & Taksim short and/or long term self-catered furnished apartments:

www.NisantasiFlats.com
www.TaximFlats.com

An update on avalable good value accommodation in Istanbul is www.flatlet-istanbul.com