As much as a pack of skitles and a hersheys.
Nothing, airplanes don't use petrol.
Radio controlled airplanes can vary in cost depending on how elaborate they are. They can range on the low end from $100.00 to over $1000.00 for the upper end ones. You can find all the options and pricing at http://www.towerhobbies.com/easyrc/airplanes/
Spaceships are MUCH faster than airplanes.
There are many different types of RC airplanes that are available for purchase. The cost of one varies depending on what type you want and the size of it.
millions and millions of dollars.once in a while they might be$100.00 or less,depending on the plane.sometimes they are less than $999.00
some aircrafts costs over multimillion. Like around 250 million for a Boeing 747.
this depends on the carrier. bur mostly around 2/3euros . important to note is that these are usually the lowest quality
There is not much point in having airplanes unless they 'take off' .
Speed, altitude, and cost.
Most likely safety, comfort and cost effectiveness increases.
Airplanes are available from a few thousand dollars into many millions.
The are much more efficient than the ones from brfore...... the are much safer and can last longer :) Hope that helps :P