Hello! I would like to upgrade my GTX660 to something faster, Here in Turkey the gpu prices are shit. GTX 780Ti sells around 1000 Turkish Liras (285USD), which is considered expensive. I found a GTX 780 for 600 Turkish Liras (170USD) and wanted to learn how good is the price performance. For comparison 2nd hand GTX 1060 3GB usually goes for 1100 Turkish Lira (315USD), 2nd Hand GTX 1050Ti goes for 800 Turkish Lira (230USD). At the same price of GTX780 we have GTX 1050, R9 280, GTX950, GTX 960, HD 7950, Rx 460. I personally don't care the power usage or heat output. I just want to have best card at best price. My Max budget is about 650 TL (185USD).
Here are the general deals in Turkey price between 550 and 650TL (157-185USD):
https://www.sahibinden.com/en/graphics-cards-desktops/used?price_min=550&price_max=650&sorting=price_asc#!