1920 DWM commercial shoulder washboard wood stock

[Telh]

Hi new to the site and new to lugers

I purchased a 1920 commercial .30 DWM luger it came with a wood shoulder stock which the numbers don't match the luger but it is a 4 digit serial number with letter I on the bottom same as the luger is also matching number 4 digit serial number with letter I

I can't seem to find any commercial luger stocks online to compare. I know these could be purchased with the pistol thru the mail back then

My main question is what are these stocks worth or go for is there a site on line that shows the differences in these stocks