Staying under $500 you can still get a Taurus 24/7 Pro. I carry a Gen 1 without difficulty. The Gen 2 has a better trigger and the Glock-style trigger safety in addition to the external safety. Excellent weapon for about $400.
If that is still too big, try the Taurus 709 Slim. Same safety and trigger as the 24/7. Half the price of a Sig, $200 less than a M&P. I have been carrying these Taurii for two years, and have put over 1,000 rounds through each one. They are reliable, accurate, and concealable. JMHO. Hope it helps.
BTW, both are available in .40SW, too.
Put your name on the backordered list at a few local shops. You'll have one in about a month (give or take). Thats how I had to go about getting mine. Super happy I did. It's great for ccw.
Also may want to consider (in no particular order))
- Kimber Aegis Ultra (9mm)
I tried this a few times and never did get a call. Guess its who you know a lot of times.
Have a shield, love it, has a thumb safety.
Had a LC9, hated it, worst trigger ever (for me).
Have M&P Compact & love it as well, but Shield is by far most comfortable ccw. Great shooter, good trigger, highly recommend for ccw.
The thickness difference is more than you would think. I have carried both and I can tell quite a difference carried IWB. I like both weapons but the Shield is definitely easier to conceal if you wear lighter clothing or tuck a shirt in.
The Shield also has a considerably better trigger than the 9c. Unless you upgrade it with Apex parts.
I love everything about the Shield except the crappy front sight dot. Mine fell out within a week of owning it. Just painted it back in with some fluorescent glow paint and am waiting on better availability of replacement sight choices.
There's also been quite a few shields popping up in the classifieds here and on armslist if you are really wanting to get one.