The HS alloy bottomed Police magazine is a collector piece in its own right in good condition...and also one of the best for functioning your Luger. Just because they are extruded or machined makes them much more valuable than an ordinary stamped magazines.
They sell on eBay occassionally and the prices I have seen in the last year or so have ranged from $75 to $150 each depending on who is selling and who is buying at any particular time.
I also own one of these fine magazines. Here is a photo of one from my Luger photo archive:
I have never owned a commercial Luger but someone else will be sure and answer your questions regarding your new purchase.
How about posting some photos of your new Luger?