My sister does USA swimming, which is the national swimming league, like AAU basketball or Pop Warner football. She practices everyday for 3 hours and has a meet almost every weekend, whether its within the Jewish Community Center League (the team is out of a JCC) or the USA league. My parents pay about $4000 to the team directly, and thats only the beginning.
Because she has D1/National potential, she swims at some really competitive meets, and for every meet, they have to pay for transportion, accommodations, a meet entry fee, and for every event she swims, she has to pay another fee just for racing that event! For the national meets (she goes about 5 a year), its about $1000 for the weekend. Regional meets are between (once every month or two months) $200-$500 for the weekend, and "local" (within New England and almost every weekend) meets are between $0-$200. My parents end up up paying at least $30,000 a year for her swimming. Luckily, because she will be getting recruited soon, they are gonna choose the school she swims at partially based on how good the scholarship and benefits are, so my parents will end up paying very little for her college.
During the summer, she goes to swimming camp in Europe for 6 weeks. This camp is normally about $12,000, but she has managed to find sponsorship or fundraising for herself every year she has gone, so my parents have never payed for camp because they rest of the season is so expensive. Every kid on the team she is on is pretty much required to go to this camp, so almost every other parent is adding another 12 grand onto the rest of the money they pay for their kid. My sister's best friend is one of 5 kids in her family swimming on this team-imagine paying about $150,000 to hand over your life to water.
While this is basically the highest level of youth swimming, you can see how costly swimming can get too. I like comment about how each level of the sport requires a different amount of financial commitment- when I swam when I was 8 during the summer, the entire season was $250, which is similar to a fall season of Pop Warner cheer.