I carry the Glock 30S .45 ACP in a SHTF IWB holster. I am thinking about getting a S&W Shield in 9mm.

I bought a Khar CM9 for right around $400 and would recommend it to anyone. Single stack 9mm that realistically can be carried in your front pocket (a lot of 9mm are marketed as "pocket carry" but for many it's a stretch).

The best you can get for what you want to spend is a no safety Shield.

The best is a G19 closely followed by a G43. The 19 being the one you would want in a real emergency. The 43 being one to settle on since it's easier to carry.

Yall do know there is a Shield in .45 now right? It's just a bit bigger than the .40.

I would advise you to look towards a mid-size/compact gun for a concealed carry; Most people can not effectively employ the very small & very difficult to grip sub-compact handguns.
With the sub-compacts, your firearm may be nice and concealed but it is useless if you can't hit your intended target when it is time to deploy your weapon.
With a little searching you can find a used glock 19 or similarly sized smith and Wesson M&P within your budget.
I would also look towards 9mm due to low recoil and cheaper ammo.

I have a Shield 40. It's become my favorite handgun. Shoots amazing for a small pistol.

Bought one yesterday

WE can all give you suggestions to look into, but ultimately it is a very personal decision that takes time to get right for you:
Your needs
Your comfort
Your carrying philosophy
Your skills and ability
Your typical daily wardrobe
Your budget

That makes the right gun for you a unique choice. One that may change a few times too

Right now I'm carrying a pocket .380 (Kahr CW380 in a Sticky Holster). Perfect for me for right now.
Handling: Feels good and Shoots well for me.
Reliability: After initial break in period, it runs flawlessly.
Size: Small and Compact which what I wanted for a "get off me gun" approach to concealed carry.
Wardrobe: No matter what I'm wearing from a suit, to khakis, to jeans to gym shorts--hot or cold weather. Sticky Holster aids in that as it stays put in my pocket when I draw AND can go IWB without a clip and stays right there due to the texture fabric.
Carry: I carry everyday no matter what.

Other pistols: many other compact pistols can do the same thing (Ruger LCP, LC9, LCR; S&W snubby, Bodyguard; Keltec, Taurus, etc...

I used to carry a larger IWB/OWB Midsize pistol but it was uncomfortable at times and was in the way with work requirements. That is now my truck gun. My pocket gun is to get me back to my truck if that is an option.

I carry just enough Boom Boom to get my azz back to my vehicle if needed

1st; Carry what you are comfortable with, or you will not carry it.2nd; Buy what you can afford. I carried a .44 at work, off duty or every day carry varies from a Ruger .357, 2 inch, or a Keltec .380, which is a "Get Off Me Gun ".

I just got a Springfield XDS .45. Time will tell but I think I'm going to like it. A lot.

S&W Shield 9mm here for every day; I carry a Taurus Judge Public Defender when hunting as my snake gun.

Winner

Glock 43, Sig p938, S&W shield

Taurus PT-111. Less than $300. 12 round double stack. Fits in the front pocket.

I like the lcp til I get back to the vehicle or house, Thas all I need.

i bought what i KNOW i will carry, no matter the dress: beretta pico. 2016 models have much better triggers. runs anything i shoot in it. world's slimmest .380 at .791 inch thick. 13 ounces loaded. minute of sternum at 7 yards. i figure it for a get-off-me gun.

I carry a Rossi 38 revolver. Fits nice in a back pocket. Very reliable.

The Limestone county jail says the Jimenez .380 won't stay in it's holester.

I Ended up getting a ruger LCP because it was the one gun I felt like I would carry with me no matter what I wear or where I go I may get another gun in the future but I think this is a good one for now.