Dermal 4000 is very cheap in US for 77$ (Rs. 4700) buts its made for 110 v.

In india same tool cost 9499 (http://www.machpowertools.com/dremel-4000-465-high-performance-rotary-multitool)

Have any one tried to use this tool (110 V , 60 mhz ) in India (220 v, 50 mhz)?

Do I need to use the voltage convert? Where can I find this converter?   
Please help.

Thank you,
Atul

yes you would definitely need a step down transformer for using this in india. fortunately these are now very common and any good electronics shop would have one. just check the wattage on the dremel and the transfer. the wattage of transformer should exceed that of dremel...

Just buy a good convertor plug 220 to 110 that's it it would be less than 10$ .

$10 converter will not work, like @mrfixit4u said - check for proper watt & voltage, else your unit will destroy. a good one will cost you between 1000-1500 bucks. check for those who specially support ps3 or other high power consuming units of 110v edition.