Cheapest available phone is Motorola F3C (Rs 600/- for Tata). Moto F3 GSM was also available few time back but after Motorola is out of Indian market I doubt its availablilty. Also, the GSM version was not that cheap too.I think Nokia 1100 is the cheapest GSM phone. Otherwise look for some Spice or Rage or Magicon phones. They may be vailable for around 1000.