This small low cost toy-grade quadcopter is an ideal trainer due to its design, low cost, and resilience.
The Hero RC Sky Matrix H1306 is a small indoor unit available from Amazon and others for about $35 to $45 US. This includes the copter, transmitter (mode 2), extra battery, USB charger, and extra props. All you need to add are AA batteries for the transmitter.
The unit incorporates an all around plastic and metal cage, ostensibly for rolling up and down walls. You can certainly do that but the main advantage is that you can hit the floor, ceiling, or almost any other obstruction without damaging the quadcopter. See my previous post for video of Matrix bashing into all manner of things with no damage. Other than that, it is a pretty standard 4 channel quadcopter with 6 axis gyro stabilization.
Documentation is terrible - a google translation from Chinese with some made-up words thrown in. Read it to get some basic ideas and a good laugh.
Relatively easy to fly, but very sensitive to throttle input, you will spend a lot of energy jockeying the throttle stick to maintain altitude. The LEDs are bright inside and will help you with the orientation of the copter. Flight time is about 5 mins on one battery and it takes about 1 to 2 hours to recharge. The inevitable crashes do not seem to mar walls or ceilings, in case your wife or mother is wondering.
This can be flown outdoors if it is really calm, but be careful as it will be harder to control than in controlled indoor environment.
There are no accessories and you cannot add any due to the small size of the unit. There is no easy way to attach a camera and it would have to be really small and light, and you would see the plastic cage when using the camera anyway.