Our family loves swimming. Although I used to sew my own cloth diapers and cloth swim covers, once I had an infant and a toddler with special needs we completely abandoned cloth and switched entirely to disposables. When my sons were still small, it was easy to find Huggies Little Swimmers or Pampers Splashers for swimming. As they outgrew those by 45 pounds at about 4 and 5 years old, I searched and searched for an affordable disposable alternative.
I've posted on special needs message boards and nobody has a great solution other than cloth covers. I ended up recently ordering Swimmates by Tena from Amazon.com. That was the best price I found and shipping was free. I ordered the smallest pack to try them out, which came out to 72 cents each. If I like them, I will order a case so they'll be cheaper.
My sons do get their pull-ups and diapers covered by Medicaid, but it does not cover swim diapers even though therapeutic swimming is part of their school program.