Chris,
You have already received much of the relevant information already it the earlier posts. To expand on that here is some more:
"how would one find out the age" - As already stated, your Luger was made in the early 1920s.
"where it was made" - It was made by the Berlin-Karlsruher Industrie-Werk (BKIW) which was formerly DWM (Deutche Waffen und Munitionsfabriken) but renamed BKIW after the war. It is a commercial piece as stated.
" ball park worth" - I do not usually assign values to guns that I have not seen personally (and sometimes not even then
) but generally speaking your gun is a very common variety and while it does have collector value it is not particularly expensive. Being in .30 caliber it is more costly to shoot than a 9mm so it is not an economical shooter. Although your gun is not particularly scarce it appears to be in nice condition so if all matching (except for magazine) I would think something in the neighborhood of $900-1100 or so. Other folks could give you better estimates.
The stock is of artillery configuration and the attaching iron looks to be an original. To really evaluate the stock much better detailed photos are required. If an authentic original it has value but that determination rests on the quality of the photos you provide.
The holster is a commercial style probably made in the US and could have been made at any time -not particularly old or valuable.