Flying solar balloons is a cheap and easy hobby, like flying a kite. A kite needs wind to lift off the ground, but a solar balloon just needs the sun and it will defy gravity and lift itself into the sky. Further more because it is using black plastic as an envelope, it doesn’t need a lot of money to build it.
Don’t forget the tether! Solar balloons can fly tens of thousands of feet high - above the jet stream. The sun will keep them hot all day so they can fly hundreds of miles in just a few hours.