We love RC helicopters here such as the Picoz Micro RC Helicopter, and other variations. If you are a fan of RC helicopters and would like to build your own then check out the site linked below. It details the steps that one guy took to build his own helicopter. No doubt, you need to have some good skills to create one of these indoor beauties and no doubt if you are not skilled then you best dish out 30 quid and buy one already made.
What makes these small helicopters great is that they are not petrol engine helicopters. They are indoor RC (battery powered) helicopters. This means you can fly this around your living room and hopefully not break any of your mothers breakables.
Good luck building and do not hesitate to link to pics of your own creations should you decide to make your own.