Playing soccer with a rolled up newspaper and paper plates for goals is the equivalent of playing whiffle ball here in the states. When you reach a higher level, costs are significant. Yes, equipment can be cheap, as cleats will run you anywhere from $25 to $400. Balls will cost $10 to $200. Then there's uniforms, additional gear and goalie equipment, if that's your position of choice.
Traveling expenses is never even considered. In order to play for top club teams, tens of thousands of dollars are required each year just for traveling. Tournaments throughout the United States and all over the world. All this, while you're just 13, 14, 15 years old...it's much different than traveling to a neighboring city, like football, baseball or hockey. Then factor in ODP, regional and national teams, which adds in even more costs.
Compared to other sports, soccer is far from being inexpensive.