Next door neighbor bought a $19.99 toy drone on line for his 8 year old grand son. Out of curiosity I weighed it - 450 grams. When Grand Pa and I gave it a test flight it easily exceeded 500 foot AGL and has a 15 minute duration.
I don't have a solution to the potential problem of drones, but I anticipate CASA FOI's hounding the suburbs in mufti stalking miscreant unlicensed 8 year olds may end up being part of the problem, but most certainly will not part of the solution.