Get some other shops to give you an estimate.The boat is only 20 years old.I see Gradys that are older then that out all the time.
Also be sure that is where the water is coming from.Sometimes a cockpit hatch cover can allow water in or a thru hull might be leaking.If you have livewell- check that for leaks as well.
Hairline cracks in the gelcoat are not uncommon.Grady builds a tough boat - it would take a good hit to split the hull.
What could be more mundane than dying of old age or of natural causes when there is death by misadventure to be pursued ? Skip