I always concealed carry either my PF9 or P3AT Kel Tec. Bought them both used at a LGS for around $400. Maybe not for everyone, but over 5 years now and never had an issue once I found the ammo they liked.
I got my full size Sig P250 9mm--with TWO mags--for $369; special offer, Bolivian contract surplus. Doubt I'll ever be lucky enough to get a new Sig that cheap again!
I've had Glocks and M&Ps and like them for what they are. But the SP2022 is another animal. It is an absolute best buy in polymer framed guns. Now that Bud's is selling new ones with night sights, even the new ones make the price point.
I recently picked up my new Glock 42 on sale for $399 at Plainfield Shooting Supplies. I may have snuck in on this under 400 thread on a technicality but thats my answer haha! But even regular price, I think he only asks about $409 (when he has them in stock) so close enough.
Ruger SR9 is nice, FNP-9 is a good choice as well. The shields seem to be very popular, but I haven't had the pleasure of shooting one yet.
I prefer my hi-point though, just what I am used to.