I found a single mag for my New Puma at a Houston area gunshow several years ago and paid about $25. I still see them around at shows for $30. They seem to be of adequate quality.
I like the pistol and have owned it for, oh, maybe 15 years. I bought it to replace a dural frame PPK in the same cailibre that I sometimes carried illegally in an appendix carry.
The pistol was made in 1962 and is a stylish and trim design. It has the same linear measurements as a J-frame Smith and is flatter. The Beretta and two spare magazines is a better carry package than the revolver and a speedloader while providing superior firepower (in exchange for inferior stopping power). The semi is certainly easier to shoot accurately than my 642 Airweight; shooting single action with my Model 38, I'm as accurate, but slower. There are obviously a lot of trade offs with either platform. I'll occasionally carry the Beretta instead of one of the .38s, but only when the chance of conflict seems slim.