What's are your skills, do you want to build it from scratch, on kit form or a mix?
Do you want it on wheel on legs..
What's about the controller, something in mind?
google is your friend, try to drill down a bit and be more precise. This forum is more an electronics guy nest, can be helpful for batteries and controllers helping but for mechanical stuff I guess that robots forums will probably be more helpful.
I'm an undergraduate student of 3rd year,in Electronics and Communication,i want to build a line following robot which will be able to pick light objects.i want to build a robot somewhat like this
and need help with the gripper.
i've worked upon Atmega8,recently participated in the wall following competition at iit bombay techfest.