You can list a figure on eBay for any amount you like, but I don't believe anyone has sold one for six hundred samolians yet. But ya' never will get that much if you don't try I suppose.
I can't find any "Nazi kroenen" having changed hands on eBay recently which probably means it's a good time to list one. Might get bidders a little excited with no recent listings.
As to what they typically sell for, I'm not sure anymore. I've seen them change hands for over two hundred dollars MIB not so long ago. No idea on loose, but since the figure is truly unique, the box itself might not mean as much as it does on some figure exclusives that are really not very different from the regular releases.
On a different note, for those longing for one of these, why not make your own? For half that two hundred you can make a much nicer, more poseable, correctly proportioned and better detailed figure, although it won't have a "pleather" tunic and breetches. It's also more satisfying if you actually play with your toys. Well, for me anyway.