Personally I would want a pretty steep discount, mould is a recurring problem, and once it gets a good toehold it is damn hard to get rid of it. Look up the heath effects of mould in buildings and the issues around its eradication to get a feel for the scope
of the problem. Given that its probably got in behind every panel and into every nook and cranny to do it right might mean removing a lot of the interior
Many years ago I delivered a 28 foot wooden yacht across the Tasman. A sweet Holman Sterling 28 called "Wild Chorus" She had been left shut up in Brisbane
for a year or so, and was full of mould. We scrubbed and bleached until it all looked pretty good, but halfway across the Tasman (It was the middle of winter and we were heading to Wellington) the mould started to flourish, all our books
started to blacken, and it marched across the overhead. we started throwing anything that wasn't essential overboard
, like blackened books
and pillows. And I am sure the experience has left me hypersensitive to mould, as I can smell it when nobody else seems to notice it, and can't stand to be in a mouldy space, coughing and struggling to breathe.
Anyway enough doom and gloom, see Untie the lines on youtube for a really serious mould problem, and a reasonably successful clean up (I hope).
If I had to tackle it I would get a full face mask and tyvek suit+gloves. A big air blower for the hatch
, and a pressure washer. once the visible mould is gone, treat it with thinwaters mix. or bleach then vinegar. and start unscrewing lining and start again to kill the mould behind all the liners. Bin all the cushions and any fabric
. You will not get the mould out of them. Don't just hit it with bleach. It might kill the mould but it always comes back. You have to physically remove the mould, then bleach it to kill any last residue.