Keep looking on e-bay and Gunbroker as they come up once in a while there. They usually go for around $250-300. Also, repeatedly look at and place WTB ads on Sturm and Subguns and eventually you'll find one.
Thanks guys, email sent to John. Of course, as always with this kind of thing, I found another source at the same time. Appreciate the heads-up. Another classic Maxim soon to be back on the firing line!