Is there a lifeproof-like case for iPhone 3GS?

I'm looking for a very sturdy, waterproof iPhone 3GS case.

Added (1). I can't upgrade to a higher device due to the high cost of buying one unlocked for a prepaid plan.

Not that I know off. You should probably just upgrade to the iPhone 4 or iPhone 5. Personally I prefer Android…

Try to look online and see if you can upgrade to the iPhone 4 or iPhone 5 at a cheaper price.

I don't think there's a life proof case for the 3GS but there's an Otterbox (defender series?) that will work to protect it but it is NOT waterproof.