They not cheap for sure, but at the end of the day I would pay $500 to clean up this issue as it looks like ticking time bomb, anyone who has had water damage knows it could run in to the 10's of thousands, so you never want to get to that point ever. It's doable yourself, just need some tools and confidence.

At some point you may want to call in a professional, even just for an estimate and see what they say.

You likely going to need to pull up some flooring and replace the pipe which you probably should do, water damage can get expensive fast if not dealt with before it happens.