German paratrooper gravity knife

[leggo]

I'm trying to sell this for a friend (not a computer guy) that will give me some knives if he can recoup his money out of this one . He bought it for $200.00 , and put $350.00 into it to have the locking mechanism replaced with the time period correct part , and an original time period correct lanyard , and the box . The spike and blade and handle looks excellent on it , overall it's very nice with no pitting or rust, looks unsharpened too . He's asking $550.00 for it to break even .
After researching these knives on the net , it looks like his price is $200 to $300 less than what they go for. This is with a money back guarantee if you aren't happy with it.