Anywhere from a few $100 to several thousand dollars. Price will vary depending on EXACT model (and there were dozens of different Lugers) its condition, and originality. Sorry that we can't give you...
Between 100 and 250 US dollars, depending upon the condition of the weapon An East German or Russian military Mak, $300 and up.
That depends on overall condition.
50-1000 USD and up depending on specifics.
There's no such thing as a 9mm Desert Eagle.