Kolkata shops:
HAQUE ELECTRONICS( cheapest option for ICs, microcontrollers: also some time sells AVR Atmega)
6/3 Madan Street
Chandni Chowk
RAILTON ELECTRONICS( probably the biggest electronics shop in Kolkata, ICs, stepper motors)
Chandni Chowk
Neeraj Trading Co
3, Chandni Chowk entrance
SUMEET INSTRUMENTS & CHEMICALS ( sells electronic kits, robotic kits from parallax, lynxmotion and other products)
[http://www.sumeetinstruments.com]
29-B Rabindra Sarani
4th floor, Room No 427
Kolkata 7000 073
You can also get scrap dc motors, stepper motors from computers, printers from roadside stalls at Chandni Chowk. U'll find many of them just don't forget to bargain
please dont buy scrap things at beginners level… buy that only if u think you are an expert