I just bought a S&W 910, which is in the 59/5900 series family and most simular to the 5904/5906 in most respects. For $230 out the door and its accurate and reliable, you can't do much better. Magazines are easy enough to find of for it uses the same magazines as the rest of the 59 series.
I have a SS 910, which is of the 59 series line of pistols. Id have to say its more handsome and more fun to shoot than my CZ, more concealable also. LEO trade in mags can be had for 19 bucks off CDNN.