I would agree with some of your suggestions, but my top five for CC under $300 would be...
#1 Bersa Thunder 9mm ultra compact 10 +1. Decent capacity, great caliber , nice size and weight for a CCW. Can't think of a bad thing to say about it.
#2 Taurus 85 Ultralight .38+P. Very easy to conceal, and comfortable to wear all day. Decent stopping power. Simple to use in a high stress situation, just point and shoot. Fits in holsters designed for J-frame S&W's. Its only downside is its capacity.
#3 Kel-Tec P3AT .380acp 6+1, Everyone should own one of these. It is the easiest to conceal decent caliber gun. I usually carry one in the pocket as a back up to my S&W 442, and still both those guns together end up weighing less than a 1911!!!! You can say bad things about its trigger, and recoil,...blah blah. But it does exactly what it was designed to do, and it does it very well.
#4 Taurus PT145 Milpro 10+1 .45acp 3rd generation. It's compact and holds a whole lot of firepower, also holsters are readilly availible. Biggest downside is its spotty quality/history. I own a 3rd gen and have never had a problem, but I wouldn't buy a used one. The earlier ones were junk. It however does have a lifetime warranty.
#5 Police Trade-Ins. As mentioned before, you can find Beretta 92/96's, lots of S&W autos, and sometimes some decent Glocks for around $300. These guns may have some holster wear, but most were shot very little. They all come in nice calibers (9mm,.40S&W,.45acp) and alot of time with 3 magazines. However these guns are almost always medium to full size variants and may be hard to use as a EDC in the summer.
I tried to make a list that covers the gambit, from tiny to full size, and from small to large caliber. I really wouldn't trust one of those bobcat/tomcats you mentioned, as they have become known as jam-o-matics for a reason, and offer little stopping power. My girlfriend however carries a Taurus 941 revolver, which is a 8rd .22magnum revolver. She is 5"1' and 95lbs, and has a hard time with larger caliber weapons, also she can't conceal very well with her body type. A snubbie fits her well, and she doesn't mind practicing alot with her .22WMR.
Everyone should be able to afford a decent CCW, and there are alot of nice options out there. I try to stay away from used guns if possible, unless it's a "classic". If money is really tight, you could always get a High-Point until you can afford something better, and the nice thing is most gun shops offer a layaway program.