We've bought one for DS this Christmas, he's 6 1/2 so I got one from a local company who have great customer service and sell spare parts cheaply as I'm pretty sure it's going to bash into a few walls! I got it 50% off during the Black Friday sales so not too expensive, about $50 Canadian, or 30 pounds.
I think he'll have a lot of fun operating it and as DH has commented soon drones will be common place delivering things everywhere and there could be a job in it for DS one day as drone operator (kinda joking here!).