Older Tube Questions

[kidsnme]

I have 2 older (17 years) Browning round tubes that had the old inner tube for the bladder. The shells are in great shape and I want to get my 2 boys into the sport. I have tried to find the inner tube with no luck so I was wondering if I could find a bladder that would fit them. Where would I start looking or would it be cheaper to just buy new tubes for them.

Also on this question where would I find smaller fins for them?
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