The longmill amp will probably be pretty decent, they used to have a bit of a following. I think it may even be 2 ohm mono stable, I am more certain of the puritan though.
The JBL 15 inch sub is also pretty decent, you would have to pay a lot more to get anything anywhere near as good.
getting a HU repaired is normally not worth it and manufacturers would be the only ones interested, a few places may entertain the idea, but I doubt it.
as for a value of any of it, I would not want to disappoint you

value is determined by what someone is willing to pay.