Help with value on a double date

[Bongos]

1918/1920 9mm. Reblued , has new grips. Comes with three mags (two matching orig to the gun). I know this is a re-arsenal to the 1920 Nato agreement. Unfortunately it was reblued (Arsenic..they don't allow this type of blueing anymore) , all numbers matched and no rust,pits of anykind, barrel is prestine. Blueing was done 50 years ago. I ask the owner why he did it, he said back then, these things were plentiful, you can buy them anywhere (litterally.. food markets, convenient store, etc...) so he didn't think much of it. The nice thing is the blueing was done correctly but with a very deep dark " Colt Python" polish blue... He has this up for sale for $900... what do you guys think??? I kind of like it as a shooter but....