i think can get from macdonalds... just tell them your kid (provided u brought 1...) like balloons.. about 1 to 3 will 'levitate' the G3... if u put more, den it will 'fly' the G3... den u can say bye bye to the G3...
Those who do party or wedding decor can help you. Try this one.
Helium can lift slightly more than one kilogram per cubic meter in air.
IOW, you'll need a balloon with a volume of 1,000 liters to lift approx 1 kg
One normal balloon (1 ft diameter) have a lifting capacity of 14 gram.
Thus you need more than 35 ballons(!) for your Canon G3 (approx 500 gram).
Get a few larger balloon instead.