I would like to see the quote where Mr Haynie actually says those exact words...
And he is selling it at that price because "An Amiga 4000 computer in mint or near-mint condition are extremely hard to find"... That may be true, but without the parts that made the A4000 an A4000... That is just not worth $500... no way...
That would be like selling a castrated dog for breading and asking full price for it....