Raul,
I am not up on the early commercial Lugers, but I have attached Simpsons Ltd site to this message. Click on the "DWM" Luger section of his site and several 1900 Commercials are for sale, in varying conditions. It appears that a 96% pistol is selling for $2600, and a 30% is at $1,000.00. Since you can look at your pistol, you can compare the condition with the advertised condition and get a close value. The values shown will be retail prices. Hope this may help you a little.
Marvin
Simpson's Site