Cheapest PC that I can recommend:
-Pentium G4400: http://www.techzone.lk/product/intel-core-pentium-processor-g4400-409501/
-GTX 750ti: http://www.techzone.lk/product/asus-gtx-750ti-2gb-409647/
-Gigabyte H110M DDR4 motherboard: http://www.techzone.lk/product/gigabyte-h110m-s2ph-410109/
-Gskill 4GB DDR4 RAM: http://www.techzone.lk/product/gskill-ddr4-2133-4gb-f4-2133c15s-4gnt-409438/
-Some decent case you can buy somewhere, both of them doesn't sell PC case. Get a used PC case which you can buy it for cheap.
-Cooler master 500w PSU: http://shop.barclays.lk/bc/itemdesc.asp?ic=14274&eq=&Tp=
If you want cheap, then you get it.
But never cheap out on PSU and Motherboard.