I bought a Mec-Gar magazine directly from Mec-Gar. I enterd MecGar on Google and got their web address. I think I bought it for less than the ones were going for on e-Bay. I wanted a nickel mag instead of the black one, which seem to be more numerous on e-Bay.
They are at
www.Mec-Gar.com
Follow the trail to luger magazines and they are available for $32 plus some change, and plus shipping. Both black and nickel are available. This should help you decide how much to bid on e-Bay if you want to do that.