Originally Posted by patches
1. CZ P07 Duty $406 @ jetguns
2. Ruger sr9 $398 @ buds
3. Bersa Thunder Pro $348 @ jetguns
4. Taurus 24/7 oss $355 @ buds
I took the liberty of re-ordering your list as I would choose them. But I have a CZ bias, so take that for what it's worth.
I'd echo the suggestion about looking at used guns. You can find some used (but like new) polymer staples (XD, Glock, M&P) for around $400 if you keep your eyes open. And for another $100-200 you can get into an excellent used Sig P226/228/229...though they're not polymer, which seems to be your primary interest.
Lots of people like the thought of owning a gun, only to run 50 rounds through it and tuck it away for a year or two. Then they sell their $600 gun for $400 or so. This is where you'll probably find the best value for your dollar.