Well here is the cheapest config you can go for-
AMD Sempron 2200+ -----------------> 2100/-
Asrock VIA KT266Pro Chipset Board----> 2400/-
256 MB DDR400 RAM -----------------> 1500/-
40GB Seagate Barracuda HDD---------> 2050/-
Cabinet+SMPS -----------------------> 900/-
5X CDRom ---------------------------> 700/-
17" Monotor -------------------------> 5500/-
Keyboard ----------------------------> 350/-
Optical Mouse -----------------------> 350/-
Basic Speakers ----------------------> 500/-
600VA UPS --------------------------> 1800/-
Total - 18,150/-
I dont think you can find a more cheaper and more decent config than this one.
I guess this helps you.