The Taurus PT-92 should come with two of those magazines. Mine did. The price seems within reason, even with one magazine. New Taurus mags run around $40. I paid $36 for a 3rd one. From what I read over at TaurusArmed.net, the O.S.S. model will run aprox. $600. The base model will be SA/DA, with an optional de-cocker on some variations.
If you need additional mags, the Mec-Gar brand seems to be the preferred one. They are less expensive and yet are very reliable. (I don't own any)