I was wondering about the following situation: First, you send up a balloon with a satellite with some thrusters built-in. As soon as the balloon reaches the geostationary height, it deploys from the balloon. After some adjustments in speed and position, it stays up there, bright and breezy! Is that achievable?
No, altitude is not the hardest thing about getting to space, it's getting enough lateral velocity so that you literally miss the earth as you fall. A weather balloon would get you to 23 miles (37 kilometres). Geostationary orbit is 22,000 miles (35,000 km), almost one thousand times that. In fact no balloon could get you that high since the earth's atmosphere ends far below that altitude and it is the density differential between the gas of the balloon and the ambient air that creates the lift that causes balloons to rise
XKCD explains it quite well in this What-If