On my other blog I mentioned the latest small drones produced by Parrot.
The prices don't seem to have fallen as I had expected. See http://www.pixmania.co.uk/high-tech-gadgets/parrot-ar-drone-2-0-elite-edition-sand/21869578-a.html?ectrans=1&ef_id=U2AUYQAABW1F-nsq%3A20140515154655%3As&gclid=CMvR8aajrr4CFckBwwod_CsA5A&merch=1&srcid=11270 as an example. Prices seem to be £230 upwards.
At those sorts of prices, I'd be far too worried about it getting stuck on a roof or in a tree and that would ruin the fun. Also, apart from the very latest lightweight designs, you'd have to be very careful near people, pets and vehicles.
On the Argos website quadcopters are available for around £55, but I've got no idea about the functionality of these.