I have build basic structure of quadcopter and looking for spacers. I did not find it in any of local hardware store. Is it called spacer or something else, most of hardware store does not even know what i am looking for. Is there any alternative for spacer, i am planning to use 10mm aluminium tube as spacer but i dont think it is right alternative for spacer.

Where can i get aluminium spacers?

Are you referring to this:
http://www.vexrobotics.com/media/catalog/product/cache/11/image/296x/5e06319eda06f020e43594a9c230972d/2/7/275-1024-washer-steel.jpg

If Yes, it's usually called a 'Washer'.

If not, provide more details or an image of what you're looking for.

i think he is looking for some thing like this http://www.apexfasteners.com/fasteners/images/Spacers_And_Standoffs.jpg

Akhilzid, you are right sir, i found one on hobbyking site but i a, looking for local source.

look at this http://www.quadkopters.com/product/hardware-and-accessories/nylon-space-m325/

DIY bhai, make your own spacers from aluminum tubes, just look for aluminum door handles.
The above could be a little difficult to find, but there's another option, look for places repairing refrigerators, they have loads and loads of copper tubes used for refrigeration coils..then pass a threaded screw and you've got "progress"  

Aa ha ! Great idea sirji, i am planning to use ball pen shell as spacer. It is ~2mm thick and perfect feet and looks great as well... but i will definately try copper tube for spacer, thanks all