How can I build this Robot?!?!?

Well, I have an idea for a robot but I'm not sure where to begin! My idea is that around a room there will be four points, each with a remote containing five ons. There will also be five shelves to match the ons. The robot will be about two feet tall with a tray on the top. Anyways, when on one is pressed, a single one of Shelf 1's contents (drink, snack, ect.) will be placed upon the robots tray with a robotic arm of some sort, causing the robot to navigate through the room until it finds the source, and then moving back to its original location. Please, if you have any information it would be greatly appreciated! Cost, parts, I need serious help! Thanks for your cooperation!